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HSC Stuff => HSC Maths Stuff => HSC Subjects + Help => HSC Standard Mathematics => Topic started by: jamonwindeyer on June 20, 2016, 12:09:38 am

Title: Standard Math Q+A Thread
Post by: jamonwindeyer on June 20, 2016, 12:09:38 am
HSC STANDARD MATHS Q&A THREAD

To go straight to posts for the new (2019+) version of the syllabus, click here

What is this thread for?
If you have general questions about the HSC Standard Maths course or how to improve in certain areas, this is the place to ask! 👌


Who can/will answer questions?
Everyone is welcome to contribute; even if you're unsure of yourself, providing different perspectives is incredibly valuable.

Please don't be dissuaded by the fact that you haven't finished Year 12, or didn't score as highly as others, or your advice contradicts something else you've seen on this thread, or whatever; none of this disqualifies you from helping others. And if you're worried you do have some sort of misconception, put it out there and someone else can clarify and modify your understanding! 

There'll be a whole bunch of other high-scoring students with their own wealths of wisdom to share with you. So you may even get multiple answers from different people offering their insights - very cool.


To ask a question or make a post, you will first need an ATAR Notes account. You probably already have one, but if you don't, it takes about four seconds to sign up - and completely free!

OTHER STANDARD MATHS RESOURCES

Original post.
Hey all! I've had a massive amount of people asking for somewhere to get some help with General Mathematics content. Now, I didn't do the course myself, but I've done a lot of it in my own studies, either at the HSC level or even at uni (yes, General Math students are better at statistics than MX2 students, I didn't learn stats until I got to university)  ;D

So, here is a place to ask questions!! I'll do my best to answer what I can, or I'd love to see you guys helping each other out as well! You'll answer it better than I could, and plus, teaching others is the best way to learn content, so helping out a peer is a win-win situation  ;D

I hope everyone is going well with their studies  ;D

PS - Remember to check out our free HSC lectures this July, including General Math!
Title: Re: General Math Q+A Thread
Post by: hammad1707 on June 23, 2016, 09:50:51 pm
Hey buddy!
I am struggling with General maths as maths is my weakest subjects.. Plus i got my Trial on this coming monday .. Can u please Assist me of how to get it done and stuff

Thank you

Regards
Hammad Ahmed
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on June 23, 2016, 11:31:13 pm
Hey buddy!
I am struggling with General maths as maths is my weakest subjects.. Plus i got my Trial on this coming monday .. Can u please Assist me of how to get it done and stuff

Thank you

Regards
Hammad Ahmed

Hey there Hammad! Welcome to the forums!  ;D

So as I mentioned above, I didn't do General Math specifically, but I did the other levels of Mathematics, and studying for them all is very much about the same thing, and that is practice!

Math is about developing a set of skills, and the best way to develop those skills is to use them. It's using them efficiently that makes the difference.It's kind of like weightlifting. To build muscle, you use the muscle. Anyone who uses their muscles will build muscle. The weightlifters are smart about when they use their muscles, and how they use them, and thus they grow muscle faster. Math is the same!!

So, you've got 3 days to study for this exam (and presumably others). You are going to need to be super time efficient! I'd suggest you do this:


This is (IMO) the absolute best way to study for Math! Excellent mix of exam practice and focused revision, so see how you go with this! You might also want to read this guide I wrote on 5 Ways to Study for Math! You might like to try some of them!

I hope this helps! Feel free to ask any more questions and I'll do my best to answer, good luck for Trials!  ;D
Title: Re: General Math Q+A Thread
Post by: tasiakuz on June 24, 2016, 05:30:37 pm
Hi! I have one weakness in general exams in that I tend not to read the question correctly and then make silly mistakes!
Do you have any exam strategies or tips that will maximise marks in the test?
Thanks so much :)
Title: Re: General Math Q+A Thread
Post by: RuiAce on June 24, 2016, 07:26:04 pm
Hi! I have one weakness in general exams in that I tend not to read the question correctly and then make silly mistakes!
Do you have any exam strategies or tips that will maximise marks in the test?
Thanks so much :)
Two simple suggestions:

Use a highlighter.
Copy out valuable pieces of information CLEARLY stating what it is on the SIDE.
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on June 24, 2016, 08:02:36 pm
Hi! I have one weakness in general exams in that I tend not to read the question correctly and then make silly mistakes!
Do you have any exam strategies or tips that will maximise marks in the test?
Thanks so much :)

Hey tasiakuz! Definitely agree with Rui, highlighting and clearly writing out all the info you are given is really useful to make sure you stay on track. I also recommend reading all the sections of a question before attempting any of them (for example, for one question, read Parts A-C before attempting A). This might give you a greater sense of direction! I know it helped me a lot to see the sort of path they were taking me on  ;D

You might also want to give this article a read! I wrote it about common mistakes made in the 2 Unit exam, some of the more general ones might be beneficial for you as well!  ;D

I hope this helps! The trick for great exam technique is to stay relaxed and keep writing! Give yourself plenty of time to read every question, and if it doesn't click right away, circle it and come back! Don't get bogged down, keep positive through the whole thing, and just move steadily, no rushing, just move as slow as you need to do the work confidently  :D
Title: Re: General Math Q+A Thread
Post by: tasiakuz on June 24, 2016, 08:16:32 pm
Thanks so much everyone! Really great info especially coming up to trials :)
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on June 24, 2016, 08:20:55 pm
Thanks so much everyone! Really great info especially coming up to trials :)

You are welcome :D Remember to come to our FREE lectures in July!! Our General Math lecturer will have heaps of exam tips for you that are more specific than Rui and I's  ;D
Title: Re: General Math Q+A Thread
Post by: Tianna Jones on June 25, 2016, 05:10:43 pm
What have you found is the most effective way to use a maths textbook? Should i be doing all the questions in order, or a few randomly?
Title: Re: General Math Q+A Thread
Post by: RuiAce on June 25, 2016, 06:00:06 pm
What have you found is the most effective way to use a maths textbook? Should i be doing all the questions in order, or a few randomly?

With the second question that's up to you. Because the whole aim of textbook questions is to allow revision for preparation for the actual stuff. Everyone works at a different pace and you need to figure out what is best for you.

Regardless you should still be doing a lot of past papers. Because for them it's just do it all.
Title: Re: General Math Q+A Thread
Post by: jakesilove on June 25, 2016, 06:57:10 pm
What have you found is the most effective way to use a maths textbook? Should i be doing all the questions in order, or a few randomly?

Definitely agree with Rui's comments. I think going through questions in your textbook is super important, and definitely necessary at some point in the year. I wouldn't be going back and doing them multiple times though (unless you're super keen); I would be doing past papers over and over again until you're so bored that the exam will feel like just another study session. Still, textbooks are great revision of content if you've forgotten how to do a specific topic (then again, I guess that's what we're here for as well!).

Jake
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on June 25, 2016, 10:32:32 pm
Definitely agree with Rui's comments. I think going through questions in your textbook is super important, and definitely necessary at some point in the year. I wouldn't be going back and doing them multiple times though (unless you're super keen); I would be doing past papers over and over again until you're so bored that the exam will feel like just another study session. Still, textbooks are great revision of content if you've forgotten how to do a specific topic (then again, I guess that's what we're here for as well!).

Jake

I'll add that if you do have a shortage of past papers (or are looking for some focused revision of a particular section), most math textbooks have a Chapter Review sort of set where they have questions on all parts of, say, Trigonometry. I used to (and indeed my teacher set aside time for this as well) do these review questions under exam conditions, and see what sorts of questions I was getting wrong! Then, if I stuffed up a specific type of question a lot (EG - using the sine rule), then I'd go back and attempt every third question in that chapter to revise. Rince, repeat  ;D

For me, the key is efficiency. Study stuff that is difficult for you and challenges you. There is no point going back and doing easy questions when you could use that time doing harder questions or, absolutely, doing a heap of past papers (but I know there aren't many for General 2 yet, so textbooks might be your backup)  ;D
Title: Re: General Math Q+A Thread
Post by: gabisperring on July 12, 2016, 08:50:14 pm
 ??? Hey I need help with this question I really can't figure it out:
"Tabitha received a 17.5% holiday loading on four weeks normal wages. She normally works a 32 hr week. Her 4wks holiday pay and loading is $2 587.90.
a) Find her normal weekly pay
b) Find her normal hourly pay rate
Thankyou!
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on July 12, 2016, 09:32:49 pm
??? Hey I need help with this question I really can't figure it out:
"Tabitha received a 17.5% holiday loading on four weeks normal wages. She normally works a 32 hr week. Her 4wks holiday pay and loading is $2 587.90.
a) Find her normal weekly pay
b) Find her normal hourly pay rate
Thankyou!

Hey there Gabi! Welcome to the forums!!  ;D I can definitely help you out here (you should also go to Steph's FREE General Math Lecture tomorrow to grab some more General Math tips!  ;D

Okay, so, we need to figure out from the number given, how much is loading and how much is the pay itself. Remember, loading adds 17.5% extra to whatever Tabitha earns normally in that 4 week block. So, she has 117.5% (100% Wage + 17.5% Loading). We can use this to calculate how much came from wages:



This is her four weekly wage, we divide this by four to get her weekly wage! This gives $551 (the actual answer might be slightly different, I rounded early up there when I maybe shouldn't have  ;) )

Okay, the hard bit is done for Part A, now to get her hourly rate, we just divide that by the 32 hours she worked! So, her hourly pay rate is 551 divided by 32, and this gives $17.21 (again, your answer might be slightly different, I rounded early!)

I hope this helps!!

Title: Re: General Math Q+A Thread
Post by: Gregs on July 12, 2016, 09:38:50 pm
Hi first post here.
In regards to your question Gabisperring
"Tabitha received a 17.5% holiday loading on four weeks normal wages. She normally works a 32 hr week. Her 4wks holiday pay and loading is $2 587.90.
a) Find her normal weekly pay
b) Find her normal hourly pay rate"

Firstly we need to work out how much money Tabitha would've earned without the 17.5% loading. To do this divide $2587.90 by 117.5% --  Because 100% is her normal wage and 17.5% is her loading so 117.5% are these two amounts combined -- This gives an answer of $2202.47
Divide $2202.47 by the 4 weeks that she worked. This works out her normal weekly pay which answers part a) ($550.62).
To "find her normal hourly pay rate" divide the amount she gets per week ($550.62) by the number of hours she works per week (32)
This should give you and answer of $17.21 -- this is the answer to b)
Title: Re: General Math Q+A Thread
Post by: Sa1998 on July 12, 2016, 09:42:53 pm
Heyyyy can someone please help me out with categorical and quantitative  data... I always mix them up
Title: Re: General Math Q+A Thread
Post by: brenden on July 12, 2016, 09:44:22 pm
Hi first post here.
In regards to your question Gabisperring
"Tabitha received a 17.5% holiday loading on four weeks normal wages. She normally works a 32 hr week. Her 4wks holiday pay and loading is $2 587.90.
a) Find her normal weekly pay
b) Find her normal hourly pay rate"

Firstly we need to work out how much money Tabitha would've earned without the 17.5% loading. To do this divide $2587.90 by 117.5% --  Because 100% is her normal wage and 17.5% is her loading so 117.5% are these two amounts combined -- This gives an answer of $2202.47
Divide $2202.47 by the 4 weeks that she worked. This works out her normal weekly pay which answers part a) ($550.62).
To "find her normal hourly pay rate" divide the amount she gets per week ($550.62) by the number of hours she works per week (32)
This should give you and answer of $17.21 -- this is the answer to b)
Thanks heaps for your awesome work Gregs. Great to have you on the forums, and so important/valuable to have valuable contributors such as yourself as part of the community. Tonight's been the busiest day in the NSW forum's history, so I can only assume we're going to need people dishing out great answers where they can like Gregs has done today!
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 12, 2016, 10:00:28 pm
Heyyyy can someone please help me out with categorical and quantitative  data... I always mix them up
If my memory serves me right this is just distinguishing between data that just associates an event with a subset or a category, contrasted to where an actual number gets associated.

Feel free to put some examples up for us to use as demos.
Title: Re: General Math Q+A Thread
Post by: conic curve on July 12, 2016, 10:03:35 pm
Thanks heaps for your awesome work Gregs. Great to have you on the forums, and so important/valuable to have valuable contributors such as yourself as part of the community. Tonight's been the busiest day in the NSW forum's history, so I can only assume we're going to need people dishing out great answers where they can like Gregs has done today!

Really, wow, that must be hard for you all  :'(
Title: Re: General Math Q+A Thread
Post by: brenden on July 12, 2016, 10:08:25 pm
Really, wow, that must be hard for you all  :'(
No, this is like the most exciting day of my bloody life.
Title: Re: General Math Q+A Thread
Post by: conic curve on July 12, 2016, 10:11:13 pm
No, this is like the most exciting day of my bloody life.

I meant like how you guys have to organise lectures and such but at the same tine there are people here on the forums who need help and if you have to help out and prepare for lectures then that's going to be too much work for you all. You get what I mean?
Title: Re: General Math Q+A Thread
Post by: brontem on July 12, 2016, 10:14:52 pm
Heyyyy can someone please help me out with categorical and quantitative  data... I always mix them up

Quantitative - where a number gets assigned either:
Discrete: eg. 0, 1, 2.. out of 10
continuous: heights of a group of people which can continuously go up and up etc

Categorical - putting something in a specific category
Nominal - does not have order e.g Male or Female
Ordinal - has value/order e.g A B C D E grade system
 ;D ;D
Title: Re: General Math Q+A Thread
Post by: brenden on July 12, 2016, 10:16:57 pm
Quantitative - where a number gets assigned either:
Discrete: eg. 0, 1, 2.. out of 10
continuous: heights of a group of people which can continuously go up and up etc

Categorical - putting something in a specific category
Nominal - does not have order e.g Male or Female
Ordinal - has value/order e.g A B C D E grade system
 ;D ;D
<3
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 12, 2016, 10:23:26 pm
Quantitative - where a number gets assigned either:
Discrete: eg. 0, 1, 2.. out of 10
continuous: heights of a group of people which can continuously go up and up etc

Categorical - putting something in a specific category
Nominal - does not have order e.g Male or Female
Ordinal - has value/order e.g A B C D E grade system
 ;D ;D
Too bad I can't describe discrete and continuous in more mathematical terminology in this thread
Title: Re: General Math Q+A Thread
Post by: brontem on July 12, 2016, 10:51:14 pm
Too bad I can't describe discrete and continuous in more mathematical terminology in this thread

Why not??
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 12, 2016, 11:02:19 pm
Why not??
True. Just didn't want the general guys to jump :P so I'll put in some informality.

You could say discrete data is formed out of the integers, or some finite set (because they can be corresponded to the integers or any counting numbers really). Discrete can be used to say how there's gaps, and the distinction between two consecutive (discrete) elements are quite obvious. Like you obviously skip over a load of rational numbers to get from one integer to the other.

You could say same goes for rational numbers as well, because you don't know where the next irrational number is but you know that one is obviously there.

Something continuous would be like all reals. An entire field of elements, one after the other and you really can't tell one apart. If you're on a continuous interval, you're basically mapping all the real numbers or just some closed/open interval that's a subset of R.

This is why height can be seen as continuous. You can say that you're 172cm tall but what if you're 172.9141244255231014597...cm tall
Title: Re: General Math Q+A Thread
Post by: brontem on July 12, 2016, 11:17:01 pm
True. Just didn't want the general guys to jump :P so I'll put in some informality.

You could say discrete data is formed out of the integers, or some finite set (because they can be corresponded to the integers or any counting numbers really). Discrete can be used to say how there's gaps, and the distinction between two consecutive (discrete) elements are quite obvious. Like you obviously skip over a load of rational numbers to get from one integer to the other.

You could say same goes for rational numbers as well, because you don't know where the next irrational number is but you know that one is obviously there.

Something continuous would be like all reals. An entire field of elements, one after the other and you really can't tell one apart. If you're on a continuous interval, you're basically mapping all the real numbers or just some closed/open interval that's a subset of R.

This is why height can be seen as continuous. You can say that you're 172cm tall but what if you're 172.9141244255231014597...cm tall

Rightio I get where you're coming from but thankfully this is only ever a multiple choice or 1 word answer to a question  :P :P
Title: Re: General Math Q+A Thread
Post by: brenden on July 13, 2016, 08:10:19 am
Bloody hell Rui. You even freaked ME out! See you soon mate haha :)
Title: Re: General Math Q+A Thread
Post by: skysailingaway on July 13, 2016, 01:55:42 pm
Hai
its my first time here and so far, i'm loving the resources and support offered on this site.
concerning general maths, i have a huge problem with sitting tests~ my mind goes blank and nothing makes sense.
plus i also find the finance topic hard to understand, what type of practice should i do to make sure i don't blank out?
~ this has happened on multiple tests now and i really don't want it to happen on my trials!
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 13, 2016, 03:02:16 pm
Hai
its my first time here and so far, i'm loving the resources and support offered on this site.
concerning general maths, i have a huge problem with sitting tests~ my mind goes blank and nothing makes sense.
plus i also find the finance topic hard to understand, what type of practice should i do to make sure i don't blank out?
~ this has happened on multiple tests now and i really don't want it to happen on my trials!
With general maths, it will be much harder to find past trial papers. If you do get your hands on them however? Great.

PastHSC has a list of the questions arranged with respect to the syllabus updated 2014. My advice is to do the past papers from the older years (keeping the recent ones for your final HSC exam), and maybe one (or two) papers under exam conditions. Figure out why your mind goes blank in tests.

(If you rely on the textbook too much, there is your answer. Textbooks, whilst not being ridiculously off, will never reflect the scope of an exam.)

Ask your school for any past papers that they might have and do them. Also redo your past exams figuring out where you went wrong and what the right frame of mind is.

Regarding the finance topic, for actual questions you may struggle on just post them on here and we'll guide you through a thought process.
Title: Re: General Math Q+A Thread
Post by: gabisperring on July 13, 2016, 04:58:59 pm
Thankyou! That was really helpful  :)
Title: Re: General Math Q+A Thread
Post by: Gregs on July 13, 2016, 07:10:52 pm
All good  :)
Title: Re: General Math Q+A Thread
Post by: Sa1998 on July 13, 2016, 07:35:12 pm
Thank you so mych
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on July 13, 2016, 11:29:32 pm
I meant like how you guys have to organise lectures and such but at the same tine there are people here on the forums who need help and if you have to help out and prepare for lectures then that's going to be too much work for you all. You get what I mean?

We love the workload, we love the challenge, and we are eager to get you guys helping us rise to the occasion  ;)
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on July 13, 2016, 11:30:38 pm
Quantitative - where a number gets assigned either:
Discrete: eg. 0, 1, 2.. out of 10
continuous: heights of a group of people which can continuously go up and up etc

Categorical - putting something in a specific category
Nominal - does not have order e.g Male or Female
Ordinal - has value/order e.g A B C D E grade system
 ;D ;D

Please know you need to be a tutor when you finish the HSC with how well you have been explaining things and answering questions lately, just saying  ;D
Title: Re: General Math Q+A Thread
Post by: brontem on July 13, 2016, 11:35:05 pm
Hahah
Please know you need to be a tutor when you finish the HSC with how well you have been explaining things and answering questions lately, just saying  ;D

Ha no worries, finally can contribute since there's questions I can actually answer  :P :P
Title: Re: General Math Q+A Thread
Post by: jakesilove on July 14, 2016, 09:12:33 am
Quantitative - where a number gets assigned either:
Discrete: eg. 0, 1, 2.. out of 10
continuous: heights of a group of people which can continuously go up and up etc

Categorical - putting something in a specific category
Nominal - does not have order e.g Male or Female
Ordinal - has value/order e.g A B C D E grade system
 ;D ;D

Legend
Title: Re: General Math Q+A Thread
Post by: skysailingaway on July 14, 2016, 10:07:23 pm
With general maths, it will be much harder to find past trial papers. If you do get your hands on them however? Great.

PastHSC has a list of the questions arranged with respect to the syllabus updated 2014. My advice is to do the past papers from the older years (keeping the recent ones for your final HSC exam), and maybe one (or two) papers under exam conditions. Figure out why your mind goes blank in tests.

(If you rely on the textbook too much, there is your answer. Textbooks, whilst not being ridiculously off, will never reflect the scope of an exam.)

Ask your school for any past papers that they might have and do them. Also redo your past exams figuring out where you went wrong and what the right frame of mind is.

Regarding the finance topic, for actual questions you may struggle on just post them on here and we'll guide you through a thought process.

thankyou for answering!
~ the link is great, I'll use your advice and complete a couple papers in exam conditions
lets hope It pays off!
Title: Re: General Math Q+A Thread
Post by: jnicko989 on July 15, 2016, 09:15:30 am
I was wondering, from the work we did in preliminary, what is assessable in HSC? The teacher said all of it, in theory - is that right?
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 15, 2016, 10:22:20 am
Now that the website is back online...
I was wondering, from the work we did in preliminary, what is assessable in HSC? The teacher said all of it, in theory - is that right?
Yes. Keep in mind that maths is different to every other subject in that the preliminary course is EXAMINABLE. Up to 20% of the final exams are allowed to include content taught in the preliminary course.

Anything goes in maths. All of it is in play.
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on July 15, 2016, 10:50:21 am
I was wondering, from the work we did in preliminary, what is assessable in HSC? The teacher said all of it, in theory - is that right?

Note also that often you'll need a bit of background knowledge from your Prelim topics to access HSC topics: So it can be assessed implicitly as well. The best way to get a gauge is to take a look at some HSC and Trial papers (since the syllabus change in 2014), and get a feel for the sorts of things that are asked. But yep, as Rui said, absolutely everything is fair game  ;D

Now that the website is back online

Minor tech issue, our legend of a dev fixed it very quickly  ;D
Title: Re: General Math Q+A Thread
Post by: jnicko989 on July 15, 2016, 12:14:35 pm
I knew about some of the ones where things were continued or skills and techniques were carried on, but I didn't know that everything could be tested. I had noticed some things had been in past papers, like mobile costs, so I have revised it briefly, but yeah, I didn't know about the 20%.

Thank you for the help - have you got any advice on how best to study for general? Just revise all of it?
Title: Re: General Math Q+A Thread
Post by: brenden on July 15, 2016, 12:26:39 pm
I knew about some of the ones where things were continued or skills and techniques were carried on, but I didn't know that everything could be tested. I had noticed some things had been in past papers, like mobile costs, so I have revised it briefly, but yeah, I didn't know about the 20%.

Thank you for the help - have you got any advice on how best to study for general? Just revise all of it?
Our General Maths lecturer has published an incredible set of notes that covers all of the Prelim content pretty briefly which is perfect for revision. We sell them on the shop here.

As for advice on how to study for it - do as many practise questions as possible, then for every question you get wrong cut it out and paste it in a book with an annotation of why you go it wrong. - Why you got tricked, why you misread the question (what word slipped up)... Then,  print out that particular page of the exam and keep all of those pages. Then, do an 'exam' made up of all the questions you got wrong  with all the pages stapled together. Keep doing that exam until you get 95%+, and if you don't know something, like legitimately don't know, then revise only that. (I.e., revise = watch videos, 'learn' the concept). If you've already learned many concepts, just go to the papers.
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 15, 2016, 04:29:38 pm
I knew about some of the ones where things were continued or skills and techniques were carried on, but I didn't know that everything could be tested. I had noticed some things had been in past papers, like mobile costs, so I have revised it briefly, but yeah, I didn't know about the 20%.

Thank you for the help - have you got any advice on how best to study for general? Just revise all of it?
Even in general, you need to keep doing past papers as brenden said. It just so happens that this is especially true for maths since maths is all about applying what you know, not going off memory.

(Which is why in my opinion, the balance between notes and papers shifts even further towards the latter for maths)
Title: Re: General Math Q+A Thread
Post by: emmaperry on July 16, 2016, 01:51:13 pm
Hi!
I was just wondering if anybody could let me know if in a General Mathematics HSC exam, they could ask us to draw a radar chart and fill in the information given for it?
I have just done a practice question from an Excel book, and they asked me to draw a radar chart, but I have never seen this in a past HSC paper before??
Thankyou!
Title: Re: General Math Q+A Thread
Post by: jakesilove on July 16, 2016, 01:57:07 pm
Hi!
I was just wondering if anybody could let me know if in a General Mathematics HSC exam, they could ask us to draw a radar chart and fill in the information given for it?
I have just done a practice question from an Excel book, and they asked me to draw a radar chart, but I have never seen this in a past HSC paper before??
Thankyou!

Hey!

I didn't go General Maths, but taking a quick look through a bunch of past papers makes me think that this is the sort of thing that they will always give you, and leave for you to interpret, rather than ask you to draw yourself.

That being said, if it is in the curriculum, they definitely COULD ask you to draw something like that. It is even more likely in Trials, where questions are often quite different to HSCs, and in fact sometimes are quite a bit harder. I would be familiar with things like drawing Radar charts, just because they could ask you to, but I wouldn't worry much about it.

Hopefully someone with more General maths experience can jump in here and help me, but I think it's fair to say you should be ready to draw it, even if it is unlikely.

Jake
Title: Re: General Math Q+A Thread
Post by: Ragdolls on July 19, 2016, 02:22:43 pm
Hi!
I was just wondering if anybody could let me know if in a General Mathematics HSC exam, they could ask us to draw a radar chart and fill in the information given for it?
I have just done a practice question from an Excel book, and they asked me to draw a radar chart, but I have never seen this in a past HSC paper before??
Thankyou!


Hey Emmaperry,

As far as I know, my maths teacher has told us to only worry about reading radar charts. I don't think we will have to draw one in the HSC exam, but just know the basics just in case. When I do past papers, the only trend I've seen is that we get radar charts and we need to know how to read and interpret them in order to answer the questions following.
Title: Re: General Math Q+A Thread
Post by: victoriad98 on July 28, 2016, 05:46:23 pm
Hey Jamon, so I really struggle in Math with conversions, like converting 1mm into 1km, or mm into L, and it really stuffs me up when I get a question where I have to do a large conversion because I just get so jumbled up! Do you know any good techniques/ways with conversions? thanks  :)
Title: Re: General Math Q+A Thread
Post by: Gregs on July 28, 2016, 06:12:20 pm
Hi Victoria
In regards to converting mm to km you simply just divide the amount of mm by 1 million (km = mm ÷ 1,000,000)
e.g. the length of the road is 490 345 956mm long, how long is this in km?

490345956 ÷ 1 000 000= 490.345956km long

I haven't seen a question asking this but I have seen questions asking you to convert the length in kilometres into length in metres then into centimetres and finally into mm.

This may seem daunting at first due to the amount of numbers required to figure these values out but all you need to remember (write in your notes) is that:

in 1km there are 1000 metres (x1000)*
in 1 metre there are 100 centimetres (x100)*
in 1cm there are 10 millimetres (x10)*
*Change the multiplication symbol to a division symbol to work back the other way
If you can remember this (which is simply the best tip i can give) and you are faced with a question like, How many mm in 560km? You can easily figure out the answer through the process of first working out how many metres then centimetres and finally millimetres.

560km x 1000 = 560 000m
560 000m x 100 = 56 000 000cm
56 000 000cm x 10 = 560 000 000mm

In regards to converting mm into L it's not really possible. You'd have to work out the volume first then convert it to metres
I found a website that is great for converting these sorts of things that also provides a description of how they do these conversions:
https://www.checkyourmath.com/index.php

Hopefully this helps
Title: Re: General Math Q+A Thread
Post by: jakesilove on July 28, 2016, 08:12:16 pm
Hey Jamon, so I really struggle in Math with conversions, like converting 1mm into 1km, or mm into L, and it really stuffs me up when I get a question where I have to do a large conversion because I just get so jumbled up! Do you know any good techniques/ways with conversions? thanks  :)

Hey!

Just a quick addition to that great answer; most of the time, you'll only need to convert from the standard unit (ie. Liters, Meters etc.) into kilo or milli versions of that unit (ie. kilograms, millimeters etc.). So, you just need to remember how they work!

For a unit (eg. m), the 'kilo' unit (eg. km) will be 1000x more that unit
For a unit (eg. m), the 'mili' unit (eg. mm) will be 1000x less that unit

If you need to convert from mili to kilo, you just multiply by 1000 to get to the normal unit, then 1000 again to get to the kilo unit! Spend some time playing around with these conversions; they're important to understand :) Thanks Gregs for the awesome response!
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on July 28, 2016, 08:18:16 pm
Hey Jamon, so I really struggle in Math with conversions, like converting 1mm into 1km, or mm into L, and it really stuffs me up when I get a question where I have to do a large conversion because I just get so jumbled up! Do you know any good techniques/ways with conversions? thanks  :)

Hey Victoria! Greg and Jake have given awesome responses, and what I'll stress from it is that I hated conversion. A little pet peeve of mine  ;D definitely you should do it in steps like Gregs did a bit further down, those involve conversions that are easier to remember! Alternatively, remember all of the prefixes like Jake suggested, which is my preferred method (being a Physicist, they teach that method there).

The other thing that messed me up a lot was conversions in 2 or 3 dimensions. For example, square centimetres to square metres. To do this, consider the formula for metres-centimetres:



To figure out the conversion of square metres to square centimetres, let's just \textbf{square both sides of this relationship}.



This is a really easy way to get the conversion rates yourself instead of remembering them! Just a neat little trick, hope it helps!  ;D
Title: Re: General Math Q+A Thread
Post by: victoriad98 on July 28, 2016, 08:29:05 pm
Thanks guys this really helped  ;D ;D
Title: Re: General Math Q+A Thread
Post by: kmorritt on July 28, 2016, 11:04:37 pm
Two simple suggestions:

Use a highlighter.
Copy out valuable pieces of information CLEARLY stating what it is on the SIDE.

thank you this is really good advice. I never used to highlight
Title: Re: General Math Q+A Thread
Post by: Gregs on August 03, 2016, 09:39:43 pm
Hi,
I was just wondering how you answer this question,
Milla enters $58 a month into a superannuation fund. It is expected that the fund averages 12%p.a compounded monthly. Find the expected value of the fund after 25 years

I get all the divide 12% by 12 to get the rate of the monthly compound and multiplying 25 by 12 but what equation do you use to add the $58 each month into the end result.

Cheers, Gregs :-\
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on August 03, 2016, 10:27:09 pm
Hi,
I was just wondering how you answer this question,
Milla enters $58 a month into a superannuation fund. It is expected that the fund averages 12%p.a compounded monthly. Find the expected value of the fund after 25 years

I get all the divide 12% by 12 to get the rate of the monthly compound and multiplying 25 by 12 but what equation do you use to add the $58 each month into the end result.

Cheers, Gregs :-\

Hey Gregs! So this is a future value of an annuity question, and there is a formula for this:



Where M is the contribution every period ($58 per month), r is the interest rate (12% divided by 12), and n is the number of periods (300 months).

Is this a formula you have learned? It's not on your Formula Sheet, but I think it's covered as part of the Financial Math part of the General Math course ;D
Title: Re: General Math Q+A Thread
Post by: Gregs on August 03, 2016, 10:33:10 pm
  Thanks Jamon, I can't remember seeing it in class but I'll try and remember it for the exam tomorrow ahah I was thinking it could've been one of those questions not in the syllabus any more.
Title: Re: General Math Q+A Thread
Post by: RuiAce on August 03, 2016, 10:36:00 pm
  Thanks Jamon, I can't remember seeing it in class but I'll try and remember it for the exam tomorrow ahah I was thinking it could've been one of those questions not in the syllabus any more.
It probably is. I found it on the outdated formula sheet but not the current one.

As in it's probably one of those not in the new syllabus
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on August 03, 2016, 10:43:55 pm
It probably is. I found it on the outdated formula sheet but not the current one.

As in it's probably one of those not in the new syllabus

Brilliant sleuthing Rui, thanks for that ;D

  Thanks Jamon, I can't remember seeing it in class but I'll try and remember it for the exam tomorrow ahah I was thinking it could've been one of those questions not in the syllabus any more.

No need to worry about it in that case Gregs, definitely not assessable anymore, good luck for your Trial!!  ;D
Title: Re: General Math Q+A Thread
Post by: stephanieazzopardi on August 04, 2016, 07:00:33 am
Hi,
I was just wondering how you answer this question,
Milla enters $58 a month into a superannuation fund. It is expected that the fund averages 12%p.a compounded monthly. Find the expected value of the fund after 25 years

I get all the divide 12% by 12 to get the rate of the monthly compound and multiplying 25 by 12 but what equation do you use to add the $58 each month into the end result.

Cheers, Gregs :-\

Hey Gregs! Okay so in the exam you may get a question like this, but you will be provided with the contribution/annuity table! So all you need to do is line up the rate with the number of periods from the table according to the question, and times that compounding factor from the table by 58. As long as everything is in months you should get the answer!! Please note: You will always be provided with a table and WILL NOT need the annuity formula as mentioned by Jamon (bloody Extension kids trying to do General ;) ) Good luck!! Please ask more questions if need be!
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on August 04, 2016, 08:46:09 am
Hey Gregs! Okay so in the exam you may get a question like this, but you will be provided with the contribution/annuity table! So all you need to do is line up the rate with the number of periods from the table according to the question, and times that compounding factor from the table by 58. As long as everything is in months you should get the answer!! Please note: You will always be provided with a table and WILL NOT need the annuity formula as mentioned by Jamon (bloody Extension kids trying to do General ;) ) Good luck!! Please ask more questions if need be!

Rekt  8)
Title: Re: General Math Q+A Thread
Post by: Gregs on August 04, 2016, 11:47:41 am
Thanks for the help guys!
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on August 04, 2016, 01:24:12 pm
Thanks for the help guys!

No problem!  ;D
Title: Re: General Math Q+A Thread
Post by: nouribrahim on August 06, 2016, 07:51:17 pm
 Can someone please explain how to solve this question?
Title: Re: General Math Q+A Thread
Post by: studybuddy7777 on August 06, 2016, 07:53:47 pm
Ok so the figures on the graph represents $1. The compounding period is every 6 months. So you half the %pa (4% i think / 2 = 2%) Then you look at the periods. 2 years = 4 periods. Then you simply line up the 2% 4 years period and times it by $25000

Hope I could help! Any further questions feel free to ask!
Title: Re: General Math Q+A Thread
Post by: nouribrahim on August 07, 2016, 02:50:20 pm
I believe the answer is 330 but the marking guide says its C
can someone explain why please?

Title: Re: General Math Q+A Thread
Post by: RuiAce on August 07, 2016, 02:53:29 pm
I believe the answer is 330 but the marking guide says its C
can someone explain why please?
Draw a compass (North-South-East-West) from B.

You're probably looking at it from the wrong perspective. Don't use the NSEW given in the diagram.

It's the bearing of A, from B.

Edit: Since Jake said it was hard without a diagram I just generated one using paint and the original image here.(http://i1164.photobucket.com/albums/q566/Rui_Tong/Capture_zpscyjxtbb6.png)
Title: Re: General Math Q+A Thread
Post by: jakesilove on August 07, 2016, 02:56:59 pm
I believe the answer is 330 but the marking guide says its C
can someone explain why please?
Hey!

So it is kind of hard to do this without drawing a picture, so I'll try describe how to get to the answer, and hopefully you can draw it to understand it better.

First, let's draw a North-South line at B. This will be parallel to the N line going through A. The bearing we are looking for is the angle between the new line NB (north line at B), going clockwise, until it hits the line AB.

Now, we know that the angle going straight from North to South at B is 180 degree (just a straight line). So, the only angle left over to figure out is the angle between the line going South from B, and the line AB. But, we can use our angle theorums to figure that out! We know that, by alternate angle on parallel lines, the angle NAB will be equal to the angle ABS (this makes way more sense when you draw it!). So, the final angle that we are looking for is 30 degree. Therefore, the total bearing will be 180 degrees plus 30 degrees, resulting in 210 degree (Making the answer C!)

Jake
Title: Re: General Math Q+A Thread
Post by: kmorritt on August 17, 2016, 06:37:50 pm
Hey,

I've been struggling with this one question for Spherical Geometry.
I was wondering if I could get some help with it? The answer is meant to be 10 500km.

Thanks,
Katie

Q. 
It is possible to fly from Perth (32oS, 115oE) to Tierra del Fuego (54oS, 65oW) on the southern tip of South America by doing directly over the South Pole along a line of longitude. Calculate the great circle distance between Perth and Tierra del Fuego (nearest km)
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on August 17, 2016, 07:18:23 pm
Hey,

I've been struggling with this one question for Spherical Geometry.
I was wondering if I could get some help with it? The answer is meant to be 10 500km.

Thanks,
Katie

Q. 
It is possible to fly from Perth (32oS, 115oE) to Tierra del Fuego (54oS, 65oW) on the southern tip of South America by doing directly over the South Pole along a line of longitude. Calculate the great circle distance between Perth and Tierra del Fuego (nearest km)

Hey Katie! So the formula you need is:



So in this case r is taken as 6400km, from you reference sheet, just the radius of the earth. The hard bit is the angle. Let's consider what is happening here.

The plane (or equivalent airborne vehicle thing) needs to fly down through the south pole and then back up to Tierra Del Fuego. To get to the south pole, it flies from 32 degrees south, to the south pole, that's an angular distance of 90-32=58 degrees, because the south pole is 90 degrees. Then, it flies UP to Tierra Del Fuego, and this is a distance of 90-54=36 degrees.

Add these together to give an angle of 94 degrees, then solve!



I hope that helps ;D
Title: Re: General Math Q+A Thread
Post by: kmorritt on August 17, 2016, 08:08:11 pm
Thank you Jamon, this has helped me a lot :)

Hey Katie! So the formula you need is:



So in this case r is taken as 6400km, from you reference sheet, just the radius of the earth. The hard bit is the angle. Let's consider what is happening here.

The plane (or equivalent airborne vehicle thing) needs to fly down through the south pole and then back up to Tierra Del Fuego. To get to the south pole, it flies from 32 degrees south, to the south pole, that's an angular distance of 90-32=58 degrees, because the south pole is 90 degrees. Then, it flies UP to Tierra Del Fuego, and this is a distance of 90-54=36 degrees.

Add these together to give an angle of 94 degrees, then solve!



I hope that helps ;D
Title: Re: General Math Q+A Thread
Post by: aimbotted on August 21, 2016, 04:10:00 pm
In the Maths Lecture powerpoint from the Notes section is the answer to question 22 incorrect?

The answer is supposedly $1622 but shouldn't it be $1209.5?
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on August 21, 2016, 05:27:24 pm
In the Maths Lecture powerpoint from the Notes section is the answer to question 22 incorrect?

The answer is supposedly $1622 but shouldn't it be $1209.5?

Hey hey! That is correct based on a quick check, and the HSC solutions seem to match :) must have been a typo!

Edit: I chatted to Steph (our General Math lecturer), during the lecture she used the new 2.0% Medicare Levy instead of the 1.5% in the question, which leads to the answer on the slides (just for clarity for anyone reading this who went to the lecture and is like "wot") ;)
Title: Re: General Math Q+A Thread
Post by: kmorritt on August 29, 2016, 11:33:08 am
Hi,
Could I please have some help with this question from spherical geometry.
Thank you :)
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on August 29, 2016, 01:14:20 pm
Hi,
Could I please have some help with this question from spherical geometry.
Thank you :)

Hey! So remember the conversion rate of longitude to time:



Now to move from Houston to Kabul, we go:



Now as we are moving to the east, our time is increasing, therefore:



Hope that makes sense! It's been a while since I've done time zones ;)
Title: Re: General Math Q+A Thread
Post by: studybuddy7777 on August 31, 2016, 08:26:46 pm
Sorry this is more of an administration question, but why doesnt any general maths questions come up on my unread topics board page thingy or sidebar?

Seeing as im a mod i want to try to contribute as much as possible!
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on August 31, 2016, 08:33:49 pm
Sorry this is more of an administration question, but why doesnt any general maths questions come up on my unread topics board page thingy or sidebar?

Seeing as im a mod i want to try to contribute as much as possible!

It wouldn't appear in the sidebar because it isn't recent (well this one is now), but as for 'Unread Posts,' did this show up? ;D
Title: Re: General Math Q+A Thread
Post by: studybuddy7777 on August 31, 2016, 09:15:19 pm
It wouldn't appear in the sidebar because it isn't recent (well this one is now), but as for 'Unread Posts,' did this show up? ;D
Yes it showed up now thanks :)
Title: Re: General Math Q+A Thread
Post by: aimbotted on September 03, 2016, 12:29:55 pm
For this question the possibilities are

3,3
5,1
5,1
4,2
4,2
3,3

so it would be 1/36 + 1/36 + 1/36 + 1/36 + 1/36 + 1/36 = 1/6

but the answer is 5/36 could anyone tell me what exactly i'm doing wrong?

question from 2013 hsc past paper
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on September 03, 2016, 12:54:51 pm
For this question the possibilities are

3,3
5,1
5,1
4,2
4,2
3,3

so it would be 1/36 + 1/36 + 1/36 + 1/36 + 1/36 + 1/36 = 1/6

but the answer is 5/36 could anyone tell me what exactly i'm doing wrong?

question from 2013 hsc past paper

Hey! So you've actually counted the same outcome (3, 3) twice. (5, 1) and (1,5) are different, (2,4) and (4,2) are different, but (3,3) and (3,3) are the same, you can't count it twice! ;D

If you draw a table of all the possible options, you might be able to visualise this better!
Title: Re: General Math Q+A Thread
Post by: aimbotted on September 03, 2016, 01:03:54 pm
wooops what a silly mistake

thanks haha
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on September 03, 2016, 01:10:06 pm
wooops what a silly mistake

thanks haha

No worries!! ;D
Title: Re: General Math Q+A Thread
Post by: RuiAce on September 03, 2016, 05:29:23 pm
For this question the possibilities are

3,3
5,1
5,1
4,2
4,2
3,3

so it would be 1/36 + 1/36 + 1/36 + 1/36 + 1/36 + 1/36 = 1/6

but the answer is 5/36 could anyone tell me what exactly i'm doing wrong?

question from 2013 hsc past paper
As a tip, try to write out your numbers such that the ordering matters. That way, your first number corresponds to die 1, \your second to die 2, and you open up opportunity for comparison.

1 5
2 4
3 3
4 2
5 1

That'll make it more obvious that 3 3 cannot be repeated.
Title: Re: General Math Q+A Thread
Post by: kmorritt on September 08, 2016, 12:44:02 pm
Hi,
could I please have some help with chapter 10 Exercise 10.07 questions.
Thank you :)
Title: Re: General Math Q+A Thread
Post by: jakesilove on September 08, 2016, 01:29:15 pm
Hi,
could I please have some help with chapter 10 Exercise 10.07 questions.
Thank you :)

Hey! The difficult part of this question is setting up the equation. We know that the strength will increase with relation to the square of the thickness. This means that



(In English, weight is proportional to thickness squared). To turn this into a real equation, we need to introduce a constant, k.



Great, so now we have a complete formula! We know that if W=1440kg, t=1.2cm. So,






For a) we let t = 0.7



For b) we let W = 3000kg



Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on September 08, 2016, 01:33:50 pm
Hi,
could I please have some help with chapter 10 Exercise 10.07 questions.
Thank you :)

Edit: Jake beat me but I'll post anyway because our answers end up different, mistake in finding your constant Jake? I'm doing mentally so not sure :P

Hi there! My working might differ slightly from the typical method you use in General Math, but it should be close! There is also an error in the wording of the question, it should read, of the cable is varied.

So, what we have here is a proportional relationship, because \(M\) grows in proportion to \(t^2\).

We can write this in two ways:



Here, \(k\) is our constant of proportionality. We can use either of these relationships to proceed (they are, in effect, the same thing) but I'll use the second one.

So we know that when \(t=1.2\), \(M=1440\). This lets us find \(k\):



What this proves is that the weight that the cable can carry is always one thousand times greater than the square of the thickness of the cable. We can use this to solve both our questions. For Question A, if we have a thickness of 0.7 centimetres:



Try your luck at Question B by substituting into the equation, the only difference being you'll have to rearrange, because you are looking for t!

You don't have to use the equation btw, you can just figure out the relationship between \(M\) and \(t^2\) and then apply it, but the equation formalises the matter ;D


Title: Re: General Math Q+A Thread
Post by: jakesilove on September 08, 2016, 04:15:13 pm
Edit: Jake beat me but I'll post anyway because our answers end up different, mistake in finding your constant Jake? I'm doing mentally so not sure :P

Hi there! My working might differ slightly from the typical method you use in General Math, but it should be close! There is also an error in the wording of the question, it should read, of the cable is varied.

So, what we have here is a proportional relationship, because \(M\) grows in proportion to \(t^2\).

We can write this in two ways:



Here, \(k\) is our constant of proportionality. We can use either of these relationships to proceed (they are, in effect, the same thing) but I'll use the second one.

So we know that when \(t=1.2\), \(M=1440\). This lets us find \(k\):



What this proves is that the weight that the cable can carry is always one thousand times greater than the square of the thickness of the cable. We can use this to solve both our questions. For Question A, if we have a thickness of 0.7 centimetres:



Try your luck at Question B by substituting into the equation, the only difference being you'll have to rearrange, because you are looking for t!

You don't have to use the equation btw, you can just figure out the relationship between \(M\) and \(t^2\) and then apply it, but the equation formalises the matter ;D

I think I must have made a calculation error somewhere, thanks for correcting!
Title: Re: General Math Q+A Thread
Post by: kmorritt on September 08, 2016, 09:24:01 pm
Thank you Jake and Jamon,
This has helped alot. Great to be able to see how to set out working.
I wasnt sure which formula to use.
Thanks again,
Katie :)
Edit: Jake beat me but I'll post anyway because our answers end up different, mistake in finding your constant Jake? I'm doing mentally so not sure :P

Hi there! My working might differ slightly from the typical method you use in General Math, but it should be close! There is also an error in the wording of the question, it should read, of the cable is varied.

So, what we have here is a proportional relationship, because \(M\) grows in proportion to \(t^2\).

We can write this in two ways:



Here, \(k\) is our constant of proportionality. We can use either of these relationships to proceed (they are, in effect, the same thing) but I'll use the second one.

So we know that when \(t=1.2\), \(M=1440\). This lets us find \(k\):



What this proves is that the weight that the cable can carry is always one thousand times greater than the square of the thickness of the cable. We can use this to solve both our questions. For Question A, if we have a thickness of 0.7 centimetres:



Try your luck at Question B by substituting into the equation, the only difference being you'll have to rearrange, because you are looking for t!

You don't have to use the equation btw, you can just figure out the relationship between \(M\) and \(t^2\) and then apply it, but the equation formalises the matter ;D
Title: Re: General Math Q+A Thread
Post by: Dani_98 on September 25, 2016, 09:52:37 pm
Hi all!

Is anyone able to explain how to work out simultaneous equations? Both the substitution and elimination method.
Thank you all :)
Title: Re: General Math Q+A Thread
Post by: RuiAce on September 25, 2016, 09:56:18 pm
Hi all!

Is anyone able to explain how to work out simultaneous equations? Both the substitution and elimination method.
Thank you all :)
How they work is just a matter of words.

Elimination works by using the operations of addition and subtraction (or possibly multiplication/division but perhaps not in general) to combine multiple equations. The way they are combined is rigged so that one of the variables disappears.

Substitution works by setting one variable equal to a giant thing first. Then, for the other equation(s), where that variable used to be, the giant thing replaces it.


If you want a demo of how to use them, that requires an example question.
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on September 25, 2016, 10:38:33 pm
Hi all!

Is anyone able to explain how to work out simultaneous equations? Both the substitution and elimination method.
Thank you all :)

Hey Dani! Steph is going to stop in and give you an explanation tomorrow, I know you couldn't stay to hear her explain it today, so hang tight and Steph will stop in ;) welcome to the forums!!
Title: Re: General Math Q+A Thread
Post by: stephanieazzopardi on September 26, 2016, 08:54:37 am
Hi all!

Is anyone able to explain how to work out simultaneous equations? Both the substitution and elimination method.
Thank you all :)

Hey Dani!

It was lovely meeting you yesterday, and i hope you got lots out of the lectures!

Ok. Simultaneous equations.
Let's look at the Substitution Method first:
Say we have to solve 2x + y = 7 and x = y - 4. Let's go through it step-by-step.
1) Number the equations (1) and (2)
2x + y = 7 (1)
x = y - 4 (2)
Note: If your equations are not in this form, try and make y or x the subject of at least one of the equations by rearranging them

Substitute (2) into (1)
2(y - 4) + y = 7

Expand, simplify and solve
2y - 8 + y = 7
2y + y = 15
3y = 15
y = 5

Substitute y = 5 into (2)
x = 5 - 4
x = 1

Write final points of intersection
x = 1, y = 5
So 1, 5.

Now, let's look at how we would solve the same two sets of equations simultaneously using the Elimination Method
Number the equations (1) and (2)
2x + y = 7 (1)
x = y - 4 (2)

Make y the subject of both equations because the two coefficients of y are equal
y = -2x + 7 (1)
y = x + 4 (2)

Subtract (2) from (1). Note: the order doesn't matter
0 = -3x + 3
Further explanation:
y - y = 0
-2x - x = -3x
7 - 4 = 3

Rearrange and solve
3x = 3
x = 1

Substitute x = 1 into (2)
y = 1 + 4
y = 5

Write final points of intersection
x = 1, y = 5
So 1, 5.

By the way, if you are asked to solve two sets of equations simultaneously, then pick the method that you find easiest and solve it like that. As you can see from the example above, you will always end up with the same answer, whether you are using the substitution or elimination method. I personally prefer the substitution method because I find it easier/faster. In the exam, they can specify for you to use either substitution or elimination method so make sure you know both really well! I really hope this helped and thank you for using the forums!
Title: Re: General Math Q+A Thread
Post by: Gregs on September 26, 2016, 10:42:24 am
Hi I was just wondering if anyone could help me with the CSSA trial exam question 28b)

The following formula can be used to calculate the number of standard drinks in a container of alcoholic beverage:

N=VA/1.27

Where:
N= number if standard drinks
V= volume of container in litres
A= the percentage of alcohol in the drink (%alc/vol)

White wine has 11.5% alc/vol.

How many millilitres of white wine is equivalent to one standard drink? Answer to the nearest millilitre

Cheers, Gregs
Title: Re: General Math Q+A Thread
Post by: RuiAce on September 26, 2016, 11:32:37 am
Hi I was just wondering if anyone could help me with the CSSA trial exam question 28b)

The following formula can be used to calculate the number of standard drinks in a container of alcoholic beverage:

N=VA/1.27

Where:
N= number if standard drinks
V= volume of container in litres
A= the percentage of alcohol in the drink (%alc/vol)

White wine has 11.5% alc/vol.

How many millilitres of white wine is equivalent to one standard drink? Answer to the nearest millilitre

Cheers, Gregs


Title: Re: General Math Q+A Thread
Post by: Gregs on September 27, 2016, 04:08:25 pm
Thanks for that, it helped a lot
I was dividing it by 11.5% rather than just 11.5 so i was getting ~11 000ml
couldn't wrap my head around it
Title: Re: General Math Q+A Thread
Post by: RuiAce on September 27, 2016, 04:10:08 pm
Thanks for that, it helped a lot
I was dividing it by 11.5% rather than just 11.5 so i was getting ~11 000ml
couldn't wrap my head around it
Yeah I suspect that's going to be a common mistake. My advice is just to double check the units whenever they give you them. For that question the units actually included the percentage sign as is.
Title: Re: General Math Q+A Thread
Post by: unnecessaryfeelings on October 04, 2016, 06:16:29 pm
**This is my first post in this website so hopefully this is how you do it!! haha**

I really suck when it comes to conversions *such as MB to GB, cm^3 to L, Watts to Kilowatts* because I don't really know much from them as I only done General Math 2 in Year 12 and only know whats on the formula sheet haha

Is there a sheet or a summary of all the conversions that I need to know in terms of measurement?

-Nicole
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 04, 2016, 07:46:12 pm
**This is my first post in this website so hopefully this is how you do it!! haha**

I really suck when it comes to conversions *such as MB to GB, cm^3 to L, Watts to Kilowatts* because I don't really know much from them as I only done General Math 2 in Year 12 and only know whats on the formula sheet haha

Is there a sheet or a summary of all the conversions that I need to know in terms of measurement?

-Nicole

Hey Nicole! Welcome to the forums! ;D

Steph's Mathematics General 2 Notes have just what you need:

(http://i.imgur.com/sQOMdOO.jpg)
(http://i.imgur.com/wWQodW7.jpg)
(http://i.imgur.com/ijwgt0V.jpg)

You can purchase the full set of notes here!


Let me know if you need a hand finding things around the site! ;D
Title: Re: General Math Q+A Thread
Post by: stephanieazzopardi on October 04, 2016, 07:57:31 pm
**This is my first post in this website so hopefully this is how you do it!! haha**

I really suck when it comes to conversions *such as MB to GB, cm^3 to L, Watts to Kilowatts* because I don't really know much from them as I only done General Math 2 in Year 12 and only know whats on the formula sheet haha

Is there a sheet or a summary of all the conversions that I need to know in terms of measurement?

-Nicole

Hey Nicole! In addition to Jamon's post (which I thank him for), these are some capacity formulas worth knowing
Hope that all helps  :)
Title: Re: General Math Q+A Thread
Post by: Daliaradosevic on October 05, 2016, 08:57:57 pm
Hey so I was just wondering whats the best most effective way to study finance maths because no matter how hard I try and do multiple practice questions of all weighing (hard or easy) I never seem to understand it!! Please suggest some ideas thank you!! :)
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 05, 2016, 10:37:35 pm
Hey so I was just wondering whats the best most effective way to study finance maths because no matter how hard I try and do multiple practice questions of all weighing (hard or easy) I never seem to understand it!! Please suggest some ideas thank you!! :)

Are you attempting the questions with your notes open and your formulas accessible? If not, that's the best way to start, make it as easy on yourself as possible :)

Otherwise, you might need to just re-teach yourself! This happens to me to, sometimes I just need to start from scratch and learn a whole topic again; usually I come away with an even stronger understanding than I had the first time I learned it. Try using your textbook, Youtube videos, anything you can find! Otherwise, feel free to post some specific questions here and we'll do our best to step you through them :)
Title: Re: General Math Q+A Thread
Post by: kmorritt on October 06, 2016, 11:05:36 pm
Hi, Ive been struggling to understand how to find an obtuse angle for this question. As you can see i got the first two completely wrong.
Could you please help? Thanks :)
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 06, 2016, 11:10:40 pm
Hi, Ive been struggling to understand how to find an obtuse angle for this question. As you can see i got the first two completely wrong.
Could you please help? Thanks :)
It's actually a bit hard to see the question; the diagram is a bit too small and thus the writing has gone tiny. So I can't exactly do the question.

So here's some advice. With cos(theta) = something negative, you can just say theta = cos-1(that negative thing)
With sin(theta) = something negative, however, you actually have to do theta = sin-1(that negative thing) + 180o

I'm not too sure how they teach it in general to tailor a response that's perfectly helpful though
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 07, 2016, 12:10:14 am
Hi, Ive been struggling to understand how to find an obtuse angle for this question. As you can see i got the first two completely wrong.
Could you please help? Thanks :)

Hey there!! So I'm going to confer with our General Lecturer on this, because I believe this is something that's a tad beyond the scope of the General course. It's in there, but right on the edge, because the syllabus asks you to:

- Establish the ratios for obtuse angles using a calculator
- Determine the sign of the ratios for obtuse angles

At no stage are you asked to specifically find obtuse angles, so this is borderline ;)

In any case, let me lend a hand with the first of those questions!



So we've got a negative angle here, uh oh! This doesn't make sense in this scenario, and as Rui correctly says, we fix this by adding 180 degrees to the angle. So:



You don't need to understand why it works, you just need to understand THAT it works (unless Steph comes along tomorrow and wrecks me for saying that) ;)

I'm not sure how much of this you need to know; because there is a whole set of rules in place to handle all sorts of different circumstances and finding obtuse angles. Note that for you, it will be far more common to be using the sine/cosine rules to find obtuse angles, not the trig ratios! I'll ask Steph to stop by tomorrow and perhaps shed some light on this for us ;D
Title: Re: General Math Q+A Thread
Post by: kmorritt on October 07, 2016, 01:40:20 pm
Hey there!! So I'm going to confer with our General Lecturer on this, because I believe this is something that's a tad beyond the scope of the General course. It's in there, but right on the edge, because the syllabus asks you to:

- Establish the ratios for obtuse angles using a calculator
- Determine the sign of the ratios for obtuse angles

At no stage are you asked to specifically find obtuse angles, so this is borderline ;)

In any case, let me lend a hand with the first of those questions!



So we've got a negative angle here, uh oh! This doesn't make sense in this scenario, and as Rui correctly says, we fix this by adding 180 degrees to the angle. So:



You don't need to understand why it works, you just need to understand THAT it works (unless Steph comes along tomorrow and wrecks me for saying that) ;)

I'm not sure how much of this you need to know; because there is a whole set of rules in place to handle all sorts of different circumstances and finding obtuse angles. Note that for you, it will be far more common to be using the sine/cosine rules to find obtuse angles, not the trig ratios! I'll ask Steph to stop by tomorrow and perhaps shed some light on this for us ;D

Hi Daliaradosevic and Jamon,
Thank you so much this does help me work out the question. I know its not a big part of the syllabus and abit beyond general maths, thats why I was suprised I found a question on it.
Youre working out is very clear and easy to understand Jamon, thank you.
When I originally tried to do it I was confused as to why if im finding an obtuse angle, the number wasnt bigger than 180, but now i understand to add 180.
Thanks again :)
Title: Re: General Math Q+A Thread
Post by: stephanieazzopardi on October 07, 2016, 01:42:44 pm
Hi Daliaradosevic and Jamon,
Thank you so much this does help me work out the question. I know its not a big part of the syllabus and abit beyond general maths, thats why I was suprised I found a question on it.
Youre working out is very clear and easy to understand Jamon, thank you.
When I originally tried to do it I was confused as to why if im finding an obtuse angle, the number wasnt bigger than 180, but now i understand to add 180.
Thanks again :)

Hi kmorritt, was going to post a 'General Math' friendly explanation, but it seems that you understand their explanations so I'm very glad :) Please keep asking questions if need be, and good luck!
Title: Re: General Math Q+A Thread
Post by: aimbotted on October 07, 2016, 01:51:07 pm
Hey Nicole! In addition to Jamon's post (which I thank him for), these are some capacity formulas worth knowing
Hope that all helps  :)

hey op, i thought 1m^3 was 1000 liters, which in turn was 1 kilo liter
Title: Re: General Math Q+A Thread
Post by: stephanieazzopardi on October 07, 2016, 01:55:41 pm
hey op, i thought 1m^3 was 1000 liters, which in turn was 1 kilo liter

Yes sorry you're right!
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 07, 2016, 02:01:05 pm
Yes sorry you're right!

I have made that fix above! ;D
Title: Re: General Math Q+A Thread
Post by: kmorritt on October 07, 2016, 06:28:35 pm
Hi kmorritt, was going to post a 'General Math' friendly explanation, but it seems that you understand their explanations so I'm very glad :) Please keep asking questions if need be, and good luck!
Hi stephanieazzopardi, thank you anyway. Yes will do :)
Title: Re: General Math Q+A Thread
Post by: sarah.murphy on October 07, 2016, 09:19:49 pm
Hi General Mathematicians   ::)
I have an issue... i love spherical geometry but... it always confusing me when we come to times zones whether I have to plus (+) or minus (-) the hours!!!  >:( can someone please explain it in layman's terms.
Please and thank you!
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 07, 2016, 09:28:37 pm
Hi General Mathematicians   ::)
I have an issue... i love spherical geometry but... it always confusing me when we come to times zones whether I have to plus (+) or minus (-) the hours!!!  >:( can someone please explain it in layman's terms.
Please and thank you!
Remember that all time zones are based off a thing called the "prime meridian" in Greenwich, England. That's the universal time centre - GMT +0

The more to the east we go, the more hours we add.
The more to the west we go, the more hours we minus.

So if we go 15o to the east of Greenwich, we add 1 hour on.
If we go 30o to the west of Greenwich, we subtract 2 hours off.


Same applies in Australia. Ignoring daylight savings time for this purpose, if we go from Sydney to Perth, which is 30o west, we subtract 2 hours off.

Also remember that in total, you only have 180o east or west at most
Title: Re: General Math Q+A Thread
Post by: aimbotted on October 08, 2016, 10:51:42 pm
Do we need to know that compound formula where you add period installments to it? Can't seem to find it in my textbook yet its relevant in the HSC past exams.
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 08, 2016, 10:59:13 pm
Do we need to know that compound formula where you add period installments to it? Can't seem to find it in my textbook yet its relevant in the HSC past exams.
Do you mean annuities? There's some information about it in page 76 of the syllabus, but I'm not entirely sure in how much depth you need to know it though.

The future value formula for an annuity doesn't seem to be in your formula sheet explicitly.
Title: Re: General Math Q+A Thread
Post by: aimbotted on October 08, 2016, 11:00:39 pm
nop, annuities are okay but its this formula or whatever it's called
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 08, 2016, 11:07:35 pm
nop, annuities are okay but its this formula or whatever it's called
That's just the annuity formula in disguise. One of them is the FV whereas the other is the PV

Reading the question, it would appear that 12000 is the future value of the annuity. Hence we are interested in the formula


Note that the above formula is for when our deposits are all $1. Because we deposit $M each month, not $1, we have an M in front of the fraction.

Also, the interest is compounded monthly.
Hence r=0.005 and n=12*10=120

I think the answer is D.
Title: Re: General Math Q+A Thread
Post by: aimbotted on October 09, 2016, 01:04:16 pm
hey thanks for that! but i just asked my teacher and he said that it was removed from 2013 and forward.

thanks again.
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 09, 2016, 02:32:28 pm
That makes sense. The formula was explicitly stated on the old formula sheet it seems.

You may want to consider PastHSC for a mapping grid of what's relevant in the current HSC exams and what's outdated, (For HSC papers before 2014)
Title: Re: General Math Q+A Thread
Post by: stephanieazzopardi on October 09, 2016, 03:07:51 pm
nop, annuities are okay but its this formula or whatever it's called

Hi aimbotted! I can assure you that you will never be asked to use such formulas for annuities. You will always be given a table of annuities, you will never have to work out the annuity/contribution factor yourself!
Title: Re: General Math Q+A Thread
Post by: AngelicOnyx on October 10, 2016, 10:18:29 am
Hi aimbotted! I can assure you that you will never be asked to use such formulas for annuities. You will always be given a table of annuities, you will never have to work out the annuity/contribution factor yourself!

Oh my god you just saved me. I've been trying to do a past paper with one of those questions and nearly had a mental breakdown because I had absolutely no idea what to do  ;D ;D
Title: Re: General Math Q+A Thread
Post by: sarah.murphy on October 10, 2016, 10:29:03 am
Remember that all time zones are based off a thing called the "prime meridian" in Greenwich, England. That's the universal time centre - GMT +0

The more to the east we go, the more hours we add.
The more to the west we go, the more hours we minus.

So if we go 15o to the east of Greenwich, we add 1 hour on.
If we go 30o to the west of Greenwich, we subtract 2 hours off.


Same applies in Australia. Ignoring daylight savings time for this purpose, if we go from Sydney to Perth, which is 30o west, we subtract 2 hours off.

Also remember that in total, you only have 180o east or west at most
Oh okay, yes yes. So it is sort of like which direction we are travelling  from a place?
Thank you so much!
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 10, 2016, 05:02:18 pm
Oh okay, yes yes. So it is sort of like which direction we are travelling  from a place?
Thank you so much!

Exactly! So from Sydney to Perth goes to the West, so we would be subtracting time from Sydney's time to get Perth's time! :)
Title: Re: General Math Q+A Thread
Post by: pughg16 on October 17, 2016, 01:27:29 pm
Does anyone know where I can get more past papers for general maths?
I have done 2015, 2014, and 2013, and what questions are the same from 2012, but I am still a bit worried about Friday....
Are there any papers getting around that are like mock HSC that someone could direct me to please??
Even more trials could help..
Thanks heaps!
Title: Re: General Math Q+A Thread
Post by: jakesilove on October 17, 2016, 01:29:38 pm
Does anyone know where I can get more past papers for general maths?
I have done 2015, 2014, and 2013, and what questions are the same from 2012, but I am still a bit worried about Friday....
Are there any papers getting around that are like mock HSC that someone could direct me to please??
Even more trials could help..
Thanks heaps!

Hey! I could be completely off, but can't you find a whole bunch of past papers on the BOSTES website, here? Click a year, hit 'G' for General Mathematics, and select the Examination Paper!
Title: Re: General Math Q+A Thread
Post by: stephanieazzopardi on October 17, 2016, 01:30:39 pm
Does anyone know where I can get more past papers for general maths?
I have done 2015, 2014, and 2013, and what questions are the same from 2012, but I am still a bit worried about Friday....
Are there any papers getting around that are like mock HSC that someone could direct me to please??
Even more trials could help..
Thanks heaps!

Hi pughg16, keep doing HSC past papers! Just keep going through them all one-by-one, 2011, 2010, 2009 and so on! That's my best advice. As long as you are doing practice questions, thats all that matters!
Title: Re: General Math Q+A Thread
Post by: pughg16 on October 17, 2016, 01:38:22 pm
So it shouldn't matter that the course has changed in some areas?
I just didnt know if the whole ourse was different, or just particular areas....I know financial mathematics is slightly different, but I have learnt how to use the formula...so thanks, will go back and do all teh years previous!!
Thanks for that!
Title: Re: General Math Q+A Thread
Post by: jakesilove on October 17, 2016, 01:44:00 pm
So it shouldn't matter that the course has changed in some areas?
I just didnt know if the whole ourse was different, or just particular areas....I know financial mathematics is slightly different, but I have learnt how to use the formula...so thanks, will go back and do all teh years previous!!
Thanks for that!

Ah true, fair enough! Just go through and do questions that are still relevant, and ignore questions that are beyond the syllabus. It's definitely really tricky for a subject that has just had a syllabus change, but yeah definitely worth going through old papers anyway.
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 17, 2016, 03:23:58 pm
This is a great place to find General Mathematics Trial Papers if that helps too! :)
Title: Re: General Math Q+A Thread
Post by: pughg16 on October 17, 2016, 04:24:59 pm
This is a great place to find General Mathematics Trial Papers if that helps too! :)

Thankyou Jamon! Thats awesome!
And thanks also Jake & stephanie...I wasn't sure whether it was worth going abck further! But I'll do the questions i can ;)
Title: Re: General Math Q+A Thread
Post by: mmmm675 on October 17, 2016, 04:58:51 pm
is this the place where we can post particular questions we need help with?
Title: Re: General Math Q+A Thread
Post by: jakesilove on October 17, 2016, 05:04:50 pm
is this the place where we can post particular questions we need help with?

Yep for sure! Post away :)
Title: Re: General Math Q+A Thread
Post by: cjrig on October 17, 2016, 05:08:29 pm
Hi i'm having trouble with this inverse proportion question. Would someone be able to solve it please?
Title: Re: General Math Q+A Thread
Post by: jakesilove on October 17, 2016, 05:12:10 pm
Hi i'm having trouble with this inverse proportion question. Would someone be able to solve it please?

Hey! If we have something that's inversely proportional, we can say that



Where v is the velocity, w is the weight the lift is carrying, and k is some constant. This makes sense; as weight increases, velocity will decrease!
To answer questions like this, we need to solve for the constant first, and then sub in the value they're looking for.

The information we are given is that, at w=320kg, v=16km/h. Therefore




Great! So, our equation is going to look like



For w=250kg, we get the answer of



Thus, the answer is B
Title: Re: General Math Q+A Thread
Post by: cjrig on October 17, 2016, 05:17:54 pm
Hey! If we have something that's inversely proportional, we can say that



Where v is the velocity, w is the weight the lift is carrying, and k is some constant. This makes sense; as weight increases, velocity will decrease!
To answer questions like this, we need to solve for the constant first, and then sub in the value they're looking for.

The information we are given is that, at w=320kg, v=16km/h. Therefore




Great! So, our equation is going to look like



For w=250kg, we get the answer of



Thus, the answer is B


Oh okay I get it now. Thank you! :)
Title: Re: General Math Q+A Thread
Post by: mmmm675 on October 17, 2016, 06:11:59 pm
could i please have some help with this question?
i was going through the slide from the lectures and couldn't figure out how the answer was achieved. 0.30 x 700 = 2100, but i'm having a blank and don't know how to use the table? thanks!

Question 5: 2014 HSC Specimen Paper
The spreadsheet shows monthly home loan repayments with interest rate changes
from February to October 2012.
(i)  Xiang’s bank approves loans for customers if their loan repayments are no more than 30% of their monthly gross salary. Xiang wanted to borrow money to buy a house. Her monthly gross salary was $7000. She applied for the loan in October 2012.
What was the maximum amount that her bank would approve for her to borrow? and the answer given is $324 420
(table is attached)
Title: Re: General Math Q+A Thread
Post by: aimbotted on October 17, 2016, 11:48:31 pm
could i please have some help with this question?
i was going through the slide from the lectures and couldn't figure out how the answer was achieved. 0.30 x 700 = 2100, but i'm having a blank and don't know how to use the table? thanks!

Question 5: 2014 HSC Specimen Paper
The spreadsheet shows monthly home loan repayments with interest rate changes
from February to October 2012.
(i)  Xiang’s bank approves loans for customers if their loan repayments are no more than 30% of their monthly gross salary. Xiang wanted to borrow money to buy a house. Her monthly gross salary was $7000. She applied for the loan in October 2012.
What was the maximum amount that her bank would approve for her to borrow? and the answer given is $324 420
(table is attached)

hey! i don't know how to do the fancy formatting everyone does but i do know how to answer your question

30% of $7000 = $2100

in october, she has $2100 for loans and the highest she can go is on $1942

this $1942 gives her a loan of $300000

however she had 2100, so 2100-1942 = $158 left

therefor, the only loans she can get are $6.47 loans

so 158/6.47 = 24.42040185

24.42040185 x 1000 = 24420 in loans

24420 + 300000 = 324420, the maximum amount she can get
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 18, 2016, 12:25:35 am
hey! i don't know how to do the fancy formatting everyone does but i do know how to answer your question

Absolute legend! You can learn that fancy formatting here if it interests you, but thanks heaps for your awesome answer! ;D
Title: Re: General Math Q+A Thread
Post by: cjrig on October 18, 2016, 04:56:41 pm
Hi, I'm having trouble figuring out this medication question. Can someone solve it please?
Title: Re: General Math Q+A Thread
Post by: jakesilove on October 18, 2016, 04:59:57 pm
Hi, I'm having trouble figuring out this medication question. Can someone solve it please?

If we have 20 drops per milliliter, and there are 600 milliliters, then there will be 20*600=12,000 drops. 4 hours = 4*60 minutes = 240 minutes. Therefore, there are 12,000 drops in 240 minutes, which is 50 drops per minute! So, the answer is C :)
Title: Re: General Math Q+A Thread
Post by: cjrig on October 18, 2016, 05:08:12 pm
If we have 20 drops per milliliter, and there are 600 milliliters, then there will be 20*600=12,000 drops. 4 hours = 4*60 minutes = 240 minutes. Therefore, there are 12,000 drops in 240 minutes, which is 50 drops per minute! So, the answer is C :)

Thanks!  ;D
Title: Re: General Math Q+A Thread
Post by: mmmm675 on October 18, 2016, 06:13:10 pm
hey! i don't know how to do the fancy formatting everyone does but i do know how to answer your question

30% of $7000 = $2100

in october, she has $2100 for loans and the highest she can go is on $1942

this $1942 gives her a loan of $300000

however she had 2100, so 2100-1942 = $158 left

therefor, the only loans she can get are $6.47 loans

so 158/6.47 = 24.42040185

24.42040185 x 1000 = 24420 in loans

24420 + 300000 = 324420, the maximum amount she can get


Awesome! thank you so much
Title: Re: General Math Q+A Thread
Post by: pughg16 on October 18, 2016, 09:03:33 pm
My internal mark is in the 70's, and my rank is 16th out of 70. Is it still possible for me to get a band 6 in general?
If so, what mark should I be aiming for?
Title: Re: General Math Q+A Thread
Post by: jakesilove on October 18, 2016, 09:13:59 pm
My internal mark is in the 70's, and my rank is 16th out of 70. Is it still possible for me to get a band 6 in general?
If so, what mark should I be aiming for?

You absolutely can still get a band 6 in general maths. I can't tell you what mark you need to aim for, except to say that it's completely possible, and likely if you put the work in. Your rank is good, your marks are good, and if you smash the HSC a band 6 is definitely within your grasp! If you have any questions, or anything we can help you out with, please post here :)
Title: Re: General Math Q+A Thread
Post by: pughg16 on October 18, 2016, 09:21:39 pm
You absolutely can still get a band 6 in general maths. I can't tell you what mark you need to aim for, except to say that it's completely possible, and likely if you put the work in. Your rank is good, your marks are good, and if you smash the HSC a band 6 is definitely within your grasp! If you have any questions, or anything we can help you out with, please post here :)

That's great. :D I was getting kind of worried, as that was one of my goals!
I have been working through past papers, but so far all seems to be pretty good!
I know where to go when in need though....thanks everyone on ATARNotes!!! ;D
Title: Re: General Math Q+A Thread
Post by: luke100 on October 19, 2016, 11:44:35 am
Hi there,

I was was just wondering what I should expect the layout/structure of the paper to be. Will there be the questions (in section 2) and then dotted lines to fill in the working or will we be given a writing booklet? It's just that in going through past papers and they are all different.

Cheers!
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 19, 2016, 11:54:32 am
Hi there,

I was was just wondering what I should expect the layout/structure of the paper to be. Will there be the questions (in section 2) and then dotted lines to fill in the working or will we be given a writing booklet? It's just that in going through past papers and they are all different.

Cheers!
The entire structure of the mathematics general course was revised in 2014.

It would appear that from 2014 onwards, there are dotted lines to fill your working. Hence this is what you should expect.
Title: Re: General Math Q+A Thread
Post by: christopherk8 on October 19, 2016, 12:32:38 pm
Hi General Mathematicians   ::)
I have an issue... i love spherical geometry but... it always confusing me when we come to times zones whether I have to plus (+) or minus (-) the hours!!!  >:( can someone please explain it in layman's terms.
Please and thank you!


Im not sure if i pressed the correct button to reply....but this is how i think of it....
ill just give this as an example....say australia is 20 degrees east and indonesia is 35 degrees east and they ask you to calculate the time in indonesia when it is say 4 o clock in sydney.....which country has the greater degrees? Indonesia. therefore you would find the hours between them and then add that amount of hours to sydney because sydney is behind indonesia.......so essentially, which ever country has the bigger degrees is the one that is ahead of the other and therefore you would have to add the hours onto the smaller country.....hope that made sense
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 19, 2016, 12:35:06 pm
Im not sure if i pressed the correct button to reply...

You did Chris, thanks for your contribution ;D
Title: Re: General Math Q+A Thread
Post by: christopherk8 on October 19, 2016, 12:45:46 pm
You did Chris, thanks for your contribution ;D

no worries!  :D
Title: Re: General Math Q+A Thread
Post by: pughg16 on October 19, 2016, 04:54:08 pm
Hi General Mathematicians   ::)
I have an issue... i love spherical geometry but... it always confusing me when we come to times zones whether I have to plus (+) or minus (-) the hours!!!  >:( can someone please explain it in layman's terms.
Please and thank you!

Hey Sarah!
My maths teacher has a little saying for this...the DAD rule. That basically stands for Different, ADd!
E.g. If you have 24* east and 48* west, as these two numbers are on different sides i.e. east and west, then add them.
However, if its 24 east and 48 east, then subtract 24 from 48. I suppose u could call this the SSUB rule (Same SUBtract  :D)

I don't know if that helps, but I always remember it that way!! DAD rule!!
Title: Re: General Math Q+A Thread
Post by: aimbotted on October 19, 2016, 05:07:25 pm
Hey Sarah!
My maths teacher has a little saying for this...the DAD rule. That basically stands for Different, ADd!
E.g. If you have 24* east and 48* west, as these two numbers are on different sides i.e. east and west, then add them.
However, if its 24 east and 48 east, then subtract 24 from 48. I suppose u could call this the SSUB rule (Same SUBtract  :D)

I don't know if that helps, but I always remember it that way!! DAD rule!!

Hey! I think thats for calculating the longitudinal difference, not for when to add the hours!

What i do it use a line to indicate whether to add the hours like this:

i hope this is what you were looking for, and not the meridian and gmt stuff
Title: Re: General Math Q+A Thread
Post by: cjrig on October 19, 2016, 05:23:45 pm
Hi, I have two questions.

1. How many kilobytes are there in 2 gigabytes? I'm having trouble solving this one!

2. (a) Alex is buying a used car which has a sale price of $13 380. In addition to the
sale price there are the following costs:
Transfer of registration $30

Stamp Duty .......

(i) Stamp Duty for this car is calculated at $3 for every $100, or part thereof,
of the sale price.


What does "part thereof" mean in this question? First time I've ever seen those words.

Any help is appreciated  ;D
Title: Re: General Math Q+A Thread
Post by: pughg16 on October 19, 2016, 05:34:35 pm
Hi, I have two questions.

1. How many kilobytes are there in 2 gigabytes? I'm having trouble solving this one!

2. (a) Alex is buying a used car which has a sale price of $13 380. In addition to the
sale price there are the following costs:
Transfer of registration $30

Stamp Duty .......

(i) Stamp Duty for this car is calculated at $3 for every $100, or part thereof,
of the sale price.


What does "part thereof" mean in this question? First time I've ever seen those words.

Any help is appreciated  ;D

Hey!!
Part thereof just means a part of 100 dollars.
I just did that q!
This means that you need to round 13380 up to 13400 so you have the parts of 100, as 80 is included as a part (80 is a part thereof of 100 if you know what I mean)
This means he will pay 134 * $3
Hope you get the part thereof bit!! Sorry, didn't explain it very well!
Title: Re: General Math Q+A Thread
Post by: pughg16 on October 19, 2016, 05:38:57 pm
Hey! I think thats for calculating the longitudinal difference, not for when to add the hours!

What i do it use a line to indicate whether to add the hours like this:

i hope this is what you were looking for, and not the meridian and gmt stuff

Sorry! :D I didn't read the post properly!!
Title: Re: General Math Q+A Thread
Post by: brontem on October 19, 2016, 05:43:01 pm
Hi, I have two questions.

1. How many kilobytes are there in 2 gigabytes? I'm having trouble solving this one!

2. (a) Alex is buying a used car which has a sale price of $13 380. In addition to the
sale price there are the following costs:
Transfer of registration $30

Stamp Duty .......

(i) Stamp Duty for this car is calculated at $3 for every $100, or part thereof,
of the sale price.


What does "part thereof" mean in this question? First time I've ever seen those words.

Any help is appreciated  ;D


Gb to kb etc conversion is x2^10 - you need to do it twice so it's x2^20
You also have to include the 2 (amount of GB) so:

2gb = 2^1 x 2^10 x 2^10
=2^21
=2097152gb :)
Title: Re: General Math Q+A Thread
Post by: cjrig on October 19, 2016, 05:55:30 pm
Hey!!
Part thereof just means a part of 100 dollars.
I just did that q!
This means that you need to round 13380 up to 13400 so you have the parts of 100, as 80 is included as a part (80 is a part thereof of 100 if you know what I mean)
This means he will pay 134 * $3
Hope you get the part thereof bit!! Sorry, didn't explain it very well!

Ahh ok. What if, for example, the sale price was $13,320, you would round it down to $13,300 right? Or would you round it up to 133,400?
Title: Re: General Math Q+A Thread
Post by: cjrig on October 19, 2016, 06:00:21 pm

Gb to kb etc conversion is x2^10 - you need to do it twice so it's x2^20
You also have to include the 2 (amount of GB) so:

2gb = 2^1 x 2^10 x 2^10
=2^21
=2097152gb :)

Ohhh okay. Why did you put 2^1 in the conversion? Sorry, I'm really bad with file size!
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 19, 2016, 06:11:17 pm
Ohhh okay. Why did you put 2^1 in the conversion? Sorry, I'm really bad with file size!
Because there's two gigabytes. Not one gigabyte.

2 Gb = 2 x 2^10 x 10^10


Technically the ^1 was not necessary.
Title: Re: General Math Q+A Thread
Post by: stephanieazzopardi on October 19, 2016, 06:25:16 pm
Ohhh okay. Why did you put 2^1 in the conversion? Sorry, I'm really bad with file size!

2^1 is just the same as writing 2 (representing 2 GB)  :)
Title: Re: General Math Q+A Thread
Post by: pughg16 on October 19, 2016, 06:26:55 pm
Ahh ok. What if, for example, the sale price was $13,320, you would round it down to $13,300 right? Or would you round it up to 133,400?

Round it up to 13,400. Every unit over 100 is included as a part of the next 100 if you get what i mean
Title: Re: General Math Q+A Thread
Post by: brontem on October 19, 2016, 06:43:35 pm
Because there's two gigabytes. Not one gigabyte.

2 Gb = 2 x 2^10 x 10^10


Technically the ^1 was not necessary.

True, unless the question is like this multiple choice (unless it's just me who got caught up ha)
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 19, 2016, 06:51:31 pm
True, unless the question is like this multiple choice (unless it's just me who got caught up ha)
The ^1 just makes it clearer. Still not necessary though :P
Title: Re: General Math Q+A Thread
Post by: cjrig on October 19, 2016, 08:28:59 pm
True, unless the question is like this multiple choice (unless it's just me who got caught up ha)
Because there's two gigabytes. Not one gigabyte.

2 Gb = 2 x 2^10 x 10^10


Technically the ^1 was not necessary.
2^1 is just the same as writing 2 (representing 2 GB)  :)

Yes that question is the one I was doing from the 2014 HSC. I put down 2^20 and was confused when I saw that the answer was 2^21. I understand now, thanks guys.  :)
Title: Re: General Math Q+A Thread
Post by: cjrig on October 19, 2016, 08:30:10 pm
Round it up to 13,400. Every unit over 100 is included as a part of the next 100 if you get what i mean

Yeah I get it now, thanks!  :)
Title: Re: General Math Q+A Thread
Post by: pughg16 on October 19, 2016, 08:49:41 pm
Yeah I get it now, thanks!  :)

No problem, glad to help!! It is a pretty easy thing to trip up on...the 'part thereof'!
Title: Re: General Math Q+A Thread
Post by: Emilyom on October 19, 2016, 11:18:50 pm
Just wondering If anyone can help me solve this multiple choice question ? thank you :)
21 Which equation correctly shows r as the subject of S = 800(1 – r)?
(A) r = 800 – S
             800
(B) r = S – 800
             800
(C) r = 800 – S
(D) r = S – 800
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 19, 2016, 11:21:11 pm
Just wondering If anyone can help me solve this multiple choice question ? thank you :)
21 Which equation correctly shows r as the subject of S = 800(1 – r)?
(A) r = 800 – S
             800
(B) r = S – 800
             800
(C) r = 800 – S
(D) r = S – 800
Title: Re: General Math Q+A Thread
Post by: aimbotted on October 20, 2016, 03:39:33 pm
how's everyone feeling for tommorow?
Title: Re: General Math Q+A Thread
Post by: pughg16 on October 20, 2016, 06:36:52 pm
how's everyone feeling for tommorow?

scared.

Can I have some help in this question please?

Ali's class sits 2 geography tests. The results of her class on the first test are:
                          58, 74, 65, 66, 73, 71, 72, 74, 62, 70
The mean was 68.5 for the first test, and calculated Standard deviation was 5.2
For the second test, the mean was 74.4 and the standard deviation was 12.4
Ali scored 62 on the first test. Calculate the mark that she needed to obtain in the second test to ensure that her performance relative to the class was maintained.
Title: Re: General Math Q+A Thread
Post by: Gregs on October 20, 2016, 06:37:17 pm

Hi Rui for this question if it wasn't a multiple choice question I'd probably do

S= 800-800r

S-800 = -800r

(S-800)/-800 = r

Why wouldn't that be right?
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 20, 2016, 06:38:34 pm
Hi Rui for this question if it wasn't a multiple choice question I'd probably do

S= 800-800r

S-800 = -800r

(S-800)/-800 = r

Why wouldn't that be right?

But whether or not you'd be marked wrong is not something for me to comment on.
Title: Re: General Math Q+A Thread
Post by: mfaith99 on October 20, 2016, 06:41:56 pm
how's everyone feeling for tommorow?
I don't know why, but I'm not feeling very stressed, usually I would be, but for this exam I feel properly prepared for once!
Title: Re: General Math Q+A Thread
Post by: Gregs on October 20, 2016, 06:47:27 pm
scared.

Can I have some help in this question please?

Ali's class sits 2 geography tests. The results of her class on the first test are:
                          58, 74, 65, 66, 73, 71, 72, 74, 62, 70
The mean was 68.5 for the first test, and calculated Standard deviation was 5.2
For the second test, the mean was 74.4 and the standard deviation was 12.4
Ali scored 62 on the first test. Calculate the mark that she needed to obtain in the second test to ensure that her performance relative to the class was maintained.

So for this it's pretty much asking how far away from the mean she is in regards to the z-scores
-1 z-score = 63.3
-2 z-scores = 58.1
so Ali is somewhere in-between these two scores to work how far off of a z-score she is minus the 63.3 by her score
= 1.3 marks
1.3 marks is 1 quarter of a standard deviation ( 1.3/5.2 = 0.25)
so that means her mark is 1.25 standard deviations away from the mean
This means to stay relative to her class Ali needs to score a mark that is -1.25 standard deviations of the mean of the second test
1.25 x 12.4 =15.5
74.4-15.5 = 58.9
Ali needs to score a mark of 58.9 for her performance to stay relative to the class

 
Title: Re: General Math Q+A Thread
Post by: Gregs on October 20, 2016, 06:48:25 pm

But whether or not you'd be marked wrong is not something for me to comment on.

Oh right I left a step out, Cheers Rui
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 20, 2016, 06:48:37 pm
I don't know why, but I'm not feeling very stressed, usually I would be, but for this exam I feel properly prepared for once!
Good on you. It means you'll kill it tomorrow
Title: Re: General Math Q+A Thread
Post by: pughg16 on October 20, 2016, 06:56:51 pm
So for this it's pretty much asking how far away from the mean she is in regards to the z-scores
-1 z-score = 63.3
-2 z-scores = 58.1
so Ali is somewhere in-between these two scores to work how far off of a z-score she is minus the 63.3 by her score
= 1.3 marks
1.3 marks is 1 quarter of a standard deviation ( 1.3/5.2 = 0.25)
so that means her mark is 1.25 standard deviations away from the mean
This means to stay relative to her class Ali needs to score a mark that is -1.25 standard deviations of the mean of the second test
1.25 x 12.4 =15.5
74.4-15.5 = 58.9
Ali needs to score a mark of 58.9 for her performance to stay relative to the class

Thankyou!
Title: Re: General Math Q+A Thread
Post by: aimbotted on October 20, 2016, 06:57:09 pm
Good on you. It means you'll kill it tomorrow

hahah thats how i always feel before every test, until i actually get in the room and realize how fucked i really am
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 20, 2016, 06:59:40 pm
hahah thats how i always feel before every test, until i actually get in the room and realize how fucked i really am
Oh nah that was me last year. And then I got high marks anyway.

So long as your good feelings are justified then it usually comes out well. If you feel good on no study then, well...
Title: Re: General Math Q+A Thread
Post by: Sssssrr on October 20, 2016, 07:22:54 pm
could someone please help me with this question?
thanks in advance
Title: Re: General Math Q+A Thread
Post by: aimbotted on October 20, 2016, 07:24:02 pm
maximum value of absolute error = 1/2 = 0.5

0.5/49 x 100 = 1.02% so 1%
Title: Re: General Math Q+A Thread
Post by: pughg16 on October 20, 2016, 09:51:18 pm
Could someone please help me with this question?
I can never get how to read these tables, or what they actually mean.
Title: Re: General Math Q+A Thread
Post by: aimbotted on October 20, 2016, 10:31:13 pm
Could someone please help me with this question?
I can never get how to read these tables, or what they actually mean.

yasssss i can

1880 x 12 x 30 = 676800

however when he pays 80000 the graph decreases by 8 years

therefor 1880 x 12 x 22 = 496320

676800-496320 = 180480 in savings

however he paid a lump sum of 80000 so 180480-80000 = 100480
Title: Re: General Math Q+A Thread
Post by: cjrig on October 20, 2016, 10:35:47 pm
Could someone please help me with this question?
I can never get how to read these tables, or what they actually mean.

The drop in the graph is when he paid the lump sum, and we can see that he finishes paying the loan at 22 years when he pays the lump sum.

He paid the loan 8 years earlier. So we need to figure out how much he would have paid if he didn't pay the lump sum 8 years earlier:

8 x 12 x 1880 = 180,480

Now we minus the lump sum from $180,840 to see how much he saved:

180,480 - 80,000 = $100,480

So he saved $100,480
Title: Re: General Math Q+A Thread
Post by: pughg16 on October 21, 2016, 08:19:33 am
yasssss i can

1880 x 12 x 30 = 676800

however when he pays 80000 the graph decreases by 8 years

therefor 1880 x 12 x 22 = 496320

676800-496320 = 180480 in savings

however he paid a lump sum of 80000 so 180480-80000 = 100480
Thankyou aimbotted!! ;D
The drop in the graph is when he paid the lump sum, and we can see that he finishes paying the loan at 22 years when he pays the lump sum.

He paid the loan 8 years earlier. So we need to figure out how much he would have paid if he didn't pay the lump sum 8 years earlier:

8 x 12 x 1880 = 180,480

Now we minus the lump sum from $180,840 to see how much he saved:

180,480 - 80,000 = $100,480

So he saved $100,480


And thankyou Cjrig!!
I now get how to do these...after much brain searching!
Thanks! :D
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 21, 2016, 08:21:46 am
Good luck to everyone sitting their exam today! ;D
Title: Re: General Math Q+A Thread
Post by: augustiscold on October 21, 2016, 12:40:30 pm
That exam was fucking disgusting TBH.
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 21, 2016, 12:43:18 pm
That exam was fucking disgusting TBH.
We will open an exam discussion thread later. You can rant there
Title: Re: General Math Q+A Thread
Post by: aimbotted on October 21, 2016, 12:45:39 pm
fucked me over so hard, this dumb cunt doesnt know how to do the 1st multiple choice question
Title: Re: General Math Q+A Thread
Post by: augustiscold on October 21, 2016, 12:52:06 pm
fucked me over so hard, this dumb cunt doesnt know how to do the 1st multiple choice question

son don't even get me started..
Title: Re: General Math Q+A Thread
Post by: pughg16 on October 21, 2016, 12:53:34 pm
We will open an exam discussion thread later. You can rant there

DID ANYONE GET THE LAST QUESTION???
Excuse capitals, but I spent probably about half an hour on it...my feeble brain just couldn't get it.....
Anyone have the same problem??
I didn't mind the rest of t...but still...
Title: Re: General Math Q+A Thread
Post by: aimbotted on October 21, 2016, 12:54:20 pm
DID ANYONE GET THE LAST QUESTION???
Excuse capitals, but I spent probably about half an hour on it...my feeble brain just couldn't get it.....
Anyone have the same problem??
I didn't mind the rest of t...but still...

yep mean was 64 and sd was 10
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 21, 2016, 12:55:57 pm
General Math Discussion Board is now up and running! ;D
Title: Re: General Math Q+A Thread
Post by: pughg16 on October 21, 2016, 12:56:11 pm
yep mean was 64 and sd was 10

Sorry, can you explain how you got that??
It totally confused me!!
Title: Re: General Math Q+A Thread
Post by: aimbotted on October 21, 2016, 01:00:36 pm
(i) mean = 88 - (s x 2.4)
mean = 88 - 2.4s

(ii) mean = 52 - (s x -1.2)
mean = 52 + 1.2s

mean = 88 - 2.4s
mean = 52 + 1.2s

88 - 2.4s = 52 + 1.2s

-2.4s - 1.2s = -3.6s

52-88 = -36

-3.6 s = -36

s = 10

thus standard deviation is 10

88 - (10x2.4)

= 64

52 - (10 x -1.2)

= 64

thus mean is 64

Title: Re: General Math Q+A Thread
Post by: pughg16 on October 21, 2016, 01:09:27 pm
(i) mean = 88 - (s x 2.4)
mean = 88 - 2.4s

(ii) mean = 52 - (s x -1.2)
mean = 52 + 1.2s

mean = 88 - 2.4s
mean = 52 + 1.2s

88 - 2.4s = 52 + 1.2s

-2.4s - 1.2s = -3.6s

52-88 = -36

-3.6 s = -36

s = 10

thus standard deviation is 10

88 - (10x2.4)

= 64

52 - (10 x -1.2)

= 64

thus mean is 64

Thanks!! U made it look so simple....and I just realised how to do it...I HATE exam nerves!!! :'(
Thanks again! :D
Title: Re: General Math Q+A Thread
Post by: aimbotted on October 21, 2016, 01:11:04 pm
Thanks!! U made it look so simple....and I just realised how to do it...I HATE exam nerves!!! :'(
Thanks again! :D

that question was hard
i wasted 30 minutes and panic kicked in until i realized i was just missing a - :(
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 21, 2016, 01:12:26 pm
Guys come on. You're free to rant all you like but please just dump it all here. Let's keep this thread cleaner for next year's cohort to ask questions :P
Title: Re: General Math Q+A Thread
Post by: lilly.n on January 31, 2017, 08:25:13 pm
hi, i need some help for this question (it is year 11 General math btw)
Title: Re: General Math Q+A Thread
Post by: RuiAce on January 31, 2017, 08:44:16 pm
hi, i need some help for this question (it is year 11 General math btw)








c) is the exact same, just that the thereafter becomes $60000

a) differs in that there is NO thereafter, as we never pay more than $140000. The next $120000 instead becomes the next $80000
Title: Re: General Math Q+A Thread
Post by: Kira Leigh on February 01, 2017, 09:44:09 pm
Hi there
We just got results back from our first HSC task and everyone was pretty confused with this one question.

B)  A kebab shop offers six different fillings for their kebabs. If Jo chooses three fillings for a kebab how many different possible choices could he make?
Everyone assumed because it said different to use the
6x5x4
Can someone please explain why we were wrong?
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on February 01, 2017, 09:46:36 pm
Hi there
We just got results back from our first HSC task and everyone was pretty confused with this one question.

B)  A kebab shop offers six different fillings for their kebabs. If Jo chooses three fillings for a kebab how many different possible choices could he make?
Everyone assumed because it said different to use the
6x5x4
Can someone please explain why we were wrong?

Hey Kira! Interesting - I'd assume you are right! However, the question never specifies that out of the 6 different fillings, that the 3 choices need to be different. That is, they could choose the same filling three times! So, it becomes 6x6x6 :) the choices don't have to be different, that's the discrepancy! Although the 6 choices are all different the choices don't have to be :)

(but then why would you choose triple of the same filling lol)
Title: Re: General Math Q+A Thread
Post by: DalvinT on February 01, 2017, 09:59:53 pm
Hey all! I've had a massive amount of people asking for somewhere to get some help with General Mathematics content. Now, I didn't do the course myself, but I've done a lot of it in my own studies, either at the HSC level or even at uni (yes, General Math students are better at statistics than MX2 students, I didn't learn stats until I got to university)  ;D

So, here is a place to ask questions!! I'll do my best to answer what I can, or I'd love to see you guys helping each other out as well! You'll answer it better than I could, and plus, teaching others is the best way to learn content, so helping out a peer is a win-win situation  ;D

I hope everyone is going well with their studies  ;D

PS - Remember to check out our free HSC lectures this July, including General Math!


Hey Jamon!!

My problem is usually with the practice exams! And I know, people have been telling me to do more practice papers to get better at those Band 6 Questions. But honestly, I think the real problem is with the "thinking process" that is involved.


For example, if we get a Band 6 Trig Question and it's very unfamiliar... What is the thinking process that you or anyone who is a Band 6 in Mathematics undergo?

i hope my question make sense hahah...
Title: Re: General Math Q+A Thread
Post by: RuiAce on February 01, 2017, 10:02:42 pm
Hi there
We just got results back from our first HSC task and everyone was pretty confused with this one question.

B)  A kebab shop offers six different fillings for their kebabs. If Jo chooses three fillings for a kebab how many different possible choices could he make?
Everyone assumed because it said different to use the
6x5x4
Can someone please explain why we were wrong?
Hey Kira! Interesting - I'd assume you are right! However, the question never specifies that out of the 6 different fillings, that the 3 choices need to be different. That is, they could choose the same filling three times! So, it becomes 6x6x6 :) the choices don't have to be different, that's the discrepancy! Although the 6 choices are all different the choices don't have to be :)

(but then why would you choose triple of the same filling lol)
I don't know enough about kebabs (shame), but just out of curiosity does the ordering of the fillings matter?
Title: Re: General Math Q+A Thread
Post by: Kira Leigh on February 01, 2017, 10:03:36 pm
Hey Kira! Interesting - I'd assume you are right! However, the question never specifies that out of the 6 different fillings, that the 3 choices need to be different. That is, they could choose the same filling three times! So, it becomes 6x6x6 :) the choices don't have to be different, that's the discrepancy! Although the 6 choices are all different the choices don't have to be :)

(but then why would you choose triple of the same filling lol)

Thank you!! That makes sense  :)
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on February 01, 2017, 10:04:30 pm

Hey Jamon!!

My problem is usually with the practice exams! And I know, people have been telling me to do more practice papers to get better at those Band 6 Questions. But honestly, I think the real problem is with the "thinking process" that is involved.

For example, if we get a Band 6 Trig Question and it's very unfamiliar... What is the thinking process that you or anyone who is a Band 6 in Mathematics undergo?

i hope my question make sense hahah...

Hey hey, it sure does! And you are going to hate the answer... It's practice. I feel like a broken record at times but practice is literally the most effective study method for any level of Math.

So when I get a Band 6 Trig question (one targeting Band 6 level students), I draw on my previous experiences of past exams, other questions I've done. I have patterns that I've seen before, I have things in the back of my mind that worked before and could work again. By the end of the HSC, almost no question could surprise me because I'd seen enough questions to know where a question needed me to go, before I ever started :)

There are of course little strategic tricks too. You should identify a topic first, for example, to narrow down your plan of attack. But the best way to get better at those unfamiliar questions, is to attempt unfamiliar questions and then learn from the solution. Never leave a math question unsolved. You should always use the solution to learn from a question, whether you can answer it on the spot or not :)
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on February 01, 2017, 10:05:44 pm
I don't know enough about kebabs (shame), but just out of curiosity does the ordering of the fillings matter?

Well if this is a HSP then the order definitely matters. To the shops who put cheese on TOP of the meat, not within or below, then shame on you. Shame.

But for a kebab the order definitely doesn't matter ;)
Title: Re: General Math Q+A Thread
Post by: RuiAce on February 01, 2017, 10:08:39 pm

Hey Jamon!!

My problem is usually with the practice exams! And I know, people have been telling me to do more practice papers to get better at those Band 6 Questions. But honestly, I think the real problem is with the "thinking process" that is involved.


For example, if we get a Band 6 Trig Question and it's very unfamiliar... What is the thinking process that you or anyone who is a Band 6 in Mathematics undergo?

i hope my question make sense hahah...
If it targets band 6, you're not supposed to have seen it before.

Hence the emphasis on "thinking process". Because you've never seen it before, you're not going to have something right up your sleeve to directly attack the problem. If you do, it means you were already at the band 6 level, which at this point in the year most people are not.

For your first few problems, you might just think for a while and not find anything. So don't be hesitant to just look at the answer.

Then, as Jamon said, look for any patterns. Compare the thought process involved in using whatever rule they applied. See if there's any reason why they, for example, made a good choice picking the sine rule over the cosine rule and etc.

Well if this is a HSP then the order definitely matters. To the shops who put cheese on TOP of the meat, not within or below, then shame on you. Shame.

But for a kebab the order definitely doesn't matter ;)
Pfft I will never have an HSP, too oily.

Well, if the order doesn't matter, don't you have to divide out by 3x2x1 (ignoring factorials at a general level because I dunno if they get taught it)
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on February 01, 2017, 10:14:07 pm
Well, if the order doesn't matter, don't you have to divide out by 3x2x1 (ignoring factorials at a general level because I dunno if they get taught it)

Hmmm... Nah, maybe the order matters then... I shall ask Steph ;D
Title: Re: General Math Q+A Thread
Post by: stephanieazzopardi on February 02, 2017, 02:30:50 pm
Hi there
We just got results back from our first HSC task and everyone was pretty confused with this one question.

B)  A kebab shop offers six different fillings for their kebabs. If Jo chooses three fillings for a kebab how many different possible choices could he make?
Everyone assumed because it said different to use the
6x5x4
Can someone please explain why we were wrong?

Hi Kira Leigh!
So the reason why you 6 x 5 x 4 wouldn't give you the correct answer is because that is not taking into account that this is an unordered selection meaning that the order doesn't matter.
To answer correctly, you need to use the combination function on your calculator or solve through a fraction.


Going back to what Jamon said about being able to choose one filling twice, I think the question and most questions like this assumes that the person wouldn't pick the same filling twice  ;D

I hope that helps and makes sense!  :)
Title: Re: General Math Q+A Thread
Post by: Celina muscat on February 03, 2017, 02:43:17 pm
Hello, I'm finding it difficult to understand the trigonometry topic and really need some help solving this math's question.
Title: Re: General Math Q+A Thread
Post by: RuiAce on February 03, 2017, 02:47:49 pm
Hello, I'm finding it difficult to understand the trigonometry topic and need some help solving this math's question.
I need to find the value of angle A in the triangle ABC. I am given the side length of AB which is 14cm and the side length of BC which is 9cm. I am then given angle C which is 48 degrees. I am meant to use the sin rule but I am unsure how to put this into a formula to solve it.
Thank you in advance  :)




Title: Re: General Math Q+A Thread
Post by: jakesilove on February 03, 2017, 02:49:48 pm
Hello, I'm finding it difficult to understand the trigonometry topic and really need some help solving this math's question.

Hey!

So, on your formula sheet, you get the Sin rule (below)

(http://i.imgur.com/vsST4Ap.png)

A, sin(a), B, sin(b), C, sin(c) etc. are shown in the triangle below

(http://mathematicsi.com/wp-content/uploads/sine-rule-triangle.png)

The thing to remember is that side A is opposite angle a. So, in your triangle, we would say that theta is opposite the 9cm side, and 48 degrees is opposite the 14cm side.


Aaaaand Rui has beat me to it.
Title: Re: General Math Q+A Thread
Post by: Snew on February 04, 2017, 05:43:06 pm
Hello! I just had a question about financial maths - in a credit card question, if there is a 55 day interest period, for example, and the due date for payment is the 25th and the person pays after this date, will they be charged interest for each day of the 55 day interest free period, or will they begin charging each day after this date? Thanks for your time  :D
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on February 05, 2017, 06:31:54 pm
Hello! I just had a question about financial maths - in a credit card question, if there is a 55 day interest period, for example, and the due date for payment is the 25th and the person pays after this date, will they be charged interest for each day of the 55 day interest free period, or will they begin charging each day after this date? Thanks for your time  :D

Hey Snew! Welcome to the forums!  ;D

The interest starts AFTER the 25th in your example - The interest free period is just that, interest free! You only pay interest for due amounts after this period  :)

Hope this helps!! Sorry for the late reply, I wanted to check my answer before I gave it, I didn't do General so wanted to be sure  8)
Title: Re: General Math Q+A Thread
Post by: stephanieazzopardi on February 06, 2017, 02:03:22 pm
Hey Snew! Welcome to the forums!  ;D

The interest starts AFTER the 25th in your example - The interest free period is just that, interest free! You only pay interest for due amounts after this period  :)

Hope this helps!! Sorry for the late reply, I wanted to check my answer before I gave it, I didn't do General so wanted to be sure  8)

Hi Snew,

Just clarifying what Jamon has awesomely said; the question will always tell you whether to count or not count the day that you purchased and/or paid for the item as part of your interest-free or non-interest-free periods.
For example, a question from the 2014 CSSA HSC Trial stated this before asking two questions:

On 21 January 2014, Michael used his credit card to purchase $1 350 worth of camping gear. The terms of Michael’s card are:

So hope that clarifies a few things! Thanks for asking and please make sure you ask us any more questions that you may have - we're happy to help  :)
Title: Re: General Math Q+A Thread
Post by: sophroberts812 on February 08, 2017, 05:07:27 pm
Hey guys I have a few maths questions that I need some help with!! They're screenshots from an online test (HotMaths - not sure if you've heard of it). It has the answers just not the working so I'd love if someone could please explain how to get to the right answer!!

Moderator action: Posts merged. At times like this, please combine all the questions in one post to avoid repeat-posting.
Title: Re: General Math Q+A Thread
Post by: legorgo18 on February 08, 2017, 05:26:53 pm
Hey guys I have a few maths questions that I need some help with!! They're screenshots from an online test (HotMaths - not sure if you've heard of it). It has the answers just not the working so I'd love if someone could please explain how to get to the right answer!!

Hi, for this one, think of it as 2/p (p^-1 is 1/p) + 3
then it will be 2/p + 3p/3
and hence answer is 2+ 3p all over p

Hope i helped :)
Title: Re: General Math Q+A Thread
Post by: legorgo18 on February 08, 2017, 05:31:19 pm
Aaaand another one....

For this ratio one, if you are having troubles with powers, try to do this m^4= m * m * m * m
and m^8 = m* m * m * m * m * m * m* m

Cross out the m, it will be none for m^4 hence 1
and there will be m * m * m * m left for m^8 and hence m^4
Title: Re: General Math Q+A Thread
Post by: legorgo18 on February 08, 2017, 05:37:06 pm
And one more...

For this one, from the info given L (big one) = A(small one) + 500
2/3 A = 1/2 (A+500)
rearranging gives 1/6 A= 250
A= 1500

So L = 1500 + 500
= 2000
Title: Re: General Math Q+A Thread
Post by: RuiAce on February 08, 2017, 05:44:33 pm
For this one, from the info given L (big one) = A(small one) + 500
2/3 A = 1/2 (A+500)
rearranging gives 1/6 A= 250
A= 1500

So L = 1500 + 500
= 2000
I'll probably format this one as well



Title: Re: General Math Q+A Thread
Post by: Snew on February 09, 2017, 07:07:31 pm
James has just turned 17 and plans on buying a car when he turns 20. He has a part time job and wants to deposit the same amount each quarter in an account earning 12% p.a. compounded quarterly. What amount:
Could be invested now to grow to $12000 in three years at 12% p.a compounded quarterly?
Cheers  ;D

Title: Re: General Math Q+A Thread
Post by: sophroberts812 on February 09, 2017, 08:10:43 pm
James has just turned 17 and plans on buying a car when he turns 20. He has a part time job and wants to deposit the same amount each quarter in an account earning 12% p.a. compounded quarterly. What amount:
Could be invested now to grow to $12000 in three years at 12% p.a compounded quarterly?
Cheers  ;D

For this one you'd use the future value formula, which is FV = PV (1 + r)^n

And from the question you get the following information...
FV = $12000
r = 3% (12% per annum / 4 quarters = 3% per quarter)
n = 12 (3 years [age 17-20] x 4 quarters per year)

So just sub into the formula...
12000 = PV (1 + 0.03)^12
Rearrange to get PV = 12000 / (1.03)^12

Therefore PV = $8416.56

So James must invest $8416.56 now to have $12000 in three years.


Hope that helps!!!!
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on February 09, 2017, 08:17:32 pm
For this one you'd use the future value formula, which is FV = PV (1 + r)^n
...
Hope that helps!!!!

Legend Soph, thanks heaps for your contribution! ;D
Title: Re: General Math Q+A Thread
Post by: Kira Leigh on February 12, 2017, 08:52:07 pm
Hi there
So I understand this is probably a silly question but when do you use the sine rule and the cosine rule? I understand the maths of it just identifying the situation of which to use is what I'm struggling with. Any tips?  :)
Title: Re: General Math Q+A Thread
Post by: RuiAce on February 12, 2017, 08:54:46 pm
Hi there
So I understand this is probably a silly question but when do you use the sine rule and the cosine rule? I understand the maths of it just identifying the situation of which to use is what I'm struggling with. Any tips?  :)
Usually you get used to when to use what with practice. However, some people do prefer the guidelines as to when to use what rule:

Finding an angle
- Given two sides and an angle - use sine rule
- Given three sides - use cosine rule

Finding a side length
- Given one side and two angles - use sine rule
- Given two sides and one angle - use cosine rule

The guidelines may help at first, but relying on them can be hard because it's easy to mix it up. Which is why with enough practice, people start becoming more reliant on intuition instead.


And there's also the rule of thumb: if one of the two doesn't work, it's most likely the other.
Title: Re: General Math Q+A Thread
Post by: kneehaha on February 15, 2017, 08:59:09 pm
Hey!

I had a math test today, which i studied for, however there were so many questions which threw me off and since half yearlies are on its way, i was wondering if i could get any general tips and ways to study effectively for a maths exam, as i want to feel as confident as possible with the HY gen maths exam and not feel like crap after like today ahahah

Thanks :)
Title: Re: General Math Q+A Thread
Post by: stephanieazzopardi on February 16, 2017, 06:51:42 pm
Hey!

I had a math test today, which i studied for, however there were so many questions which threw me off and since half yearlies are on its way, i was wondering if i could get any general tips and ways to study effectively for a maths exam, as i want to feel as confident as possible with the HY gen maths exam and not feel like crap after like today ahahah

Thanks :)

Hi there!

Ok so basically there are multiple ways that you can approach your study for any General Math exam, although it's all about finding what works for you best! Are you doing lots of practice questions, or are you just staring at your textbook for hours? Are you putting yourself under exam conditions before the exam and completing a past paper within the 2.5 hours?

When studying for a General Math exam, I would sit myself in a quiet room, go through all the past papers I could find and highlight the questions I found were a little tricky at first glance (like I couldn't just do it in my head). You need to make sure you aren't studying in your comfort zone. You need to make sure you are pushing yourself out of your comfort zone and studying really tough questions so that when you get into the exam and are confronted with these questions that are designed to throw you under time/exam pressure, you will already have been exposed to similar questions. This will maximise your chance of getting the Band 6 questions correct. (Tip: usually trial HSC papers are a lot more tough than HSC papers, so make sure you are getting some of your practice questions from there!)

Another thing I liked to do as I was studying/completing practice questions for a Gen Math exam was to write out the formulas that I was required to use for each question and highlight them/made them obvious so that when I flicked back through my exercise book before the exam all the formulas grabbed my attention. This definitely helped me to remember the formulas and I barely had to flick back to the lengthy formula sheet which was great as it saved me so much time in the exam!

I hope this helps. At the end of the day, the best way to study for any Math exam is PRACTICE, PRACTICE, PRACTICE until all the questions seem somewhat "easy".

Thank you and good luck! Please feel free to ask for help on any tough practice questions that you come by in preparation for your half yearly's  ;D
Title: General Math Q+A Thread
Post by: emilybrooks99 on February 19, 2017, 05:33:03 pm
I'm not sure if I post questions on this thread or as a new topic thing like I did last time. I guess I'll just ask here and if I'm in the wrong spot let me know.
I'm having trouble with radical surveys. The worked example in my textbook only shows how to work it out if all the shapes are triangles. However the question I am doing at the moment (number 2a) looks like this (http://uploads.tapatalk-cdn.com/20170218/b0a431d7f39ba80573f87e29bbbe04fa.jpg)
Can someone please talk me through how to work it out
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on February 19, 2017, 07:49:12 pm
I'm not sure if I post questions on this thread or as a new topic thing like I did last time. I guess I'll just ask here and if I'm in the wrong spot let me know.
I'm having trouble with radical surveys. The worked example in my textbook only shows how to work it out if all the shapes are triangles. However the question I am doing at the moment (number 2a) looks like this (http://uploads.tapatalk-cdn.com/20170218/b0a431d7f39ba80573f87e29bbbe04fa.jpg)
Can someone please talk me through how to work it out

Hey Emily! I'll let our General Math lecturer Steph help you out when she next pops in, but definitely all good to post here! Or start a new topic - Both are totally fine ;D
Title: Re: General Math Q+A Thread
Post by: stephanieazzopardi on February 20, 2017, 10:41:24 am
I'm not sure if I post questions on this thread or as a new topic thing like I did last time. I guess I'll just ask here and if I'm in the wrong spot let me know.
I'm having trouble with radical surveys. The worked example in my textbook only shows how to work it out if all the shapes are triangles. However the question I am doing at the moment (number 2a) looks like this (http://uploads.tapatalk-cdn.com/20170218/b0a431d7f39ba80573f87e29bbbe04fa.jpg)
Can someone please talk me through how to work it out

Hi Emily!

Happy to help with this question. You can actually find step-by-step instructions on how to draw a scale diagram for a plane-table radial survey on pages 181-182 of your textbook.
Ok so I'll give you a run down of how I drew the scale diagram as shown in the images below.

So firstly you'll need a compass and a ruler.

The rest should be self explanatory through the images of my working out as shown below.

(http://i.imgur.com/LVkcKt1.jpg)
(http://i.imgur.com/Dva6CGr.png)

Hope this helps  :)
Title: Re: General Math Q+A Thread
Post by: Droolv on March 04, 2017, 12:50:30 pm
(http://uploads.tapatalk-cdn.com/20170303/37b7e6d1c5c95cd4f3f432498ef82647.jpg)

Hey all, can someone help with this question??

Thanks
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on March 04, 2017, 01:06:34 pm
(http://uploads.tapatalk-cdn.com/20170303/37b7e6d1c5c95cd4f3f432498ef82647.jpg)

Hey all, can someone help with this question??

Thanks

Hi there! So this is just a really tough question on areas of compound figures - We have to find the areas of all the smaller parts and use that to find the whole thing. In this case, we need to find the areas of the circles, and subtract them from the rectangle.

The rectangles area is just given by base times height;



Now we'll find the areas of the three circles. The area of a circle is \(A=\pi r^2\), but we are given the diameter of each circle (from one side of the circle to the other). So we need to cut that in half to get the radius to use in the formula. First, the big circle:



Now the two smaller ones are the same:



So the total area is the area of the rectangle, subtract the area of the circles (one big, two small):



Note we've just factorised by pulling out \(6x^2\) at the end there - A is the answer!! I hope that helps, let me know if any of it is a little confusing ;D
Title: Re: General Math Q+A Thread
Post by: Snew on March 16, 2017, 10:05:05 pm
Hey!

I had a math test today, which i studied for, however there were so many questions which threw me off and since half yearlies are on its way, i was wondering if i could get any general tips and ways to study effectively for a maths exam, as i want to feel as confident as possible with the HY gen maths exam and not feel like crap after like today ahahah

Thanks :)


Hey! I'm not an ATAR Notes legend or anything, but past papers are honestly the way to go, even if you get to a question that you're not sure of as it helps you to identify what specific knowledge you need for the question (financial, algebra etc) and you can seek specific help on that :) if you need some practice papers definitely use this website!! http://users.tpg.com.au/nanahcub/otherpapers.html heaps of past trial papers you can go through, I've found it's really helped :)
Title: Re: General Math Q+A Thread
Post by: damecj on March 25, 2017, 08:13:20 pm
Just struggling with this question any help would be appreciated
Title: Re: General Math Q+A Thread
Post by: jakesilove on March 25, 2017, 10:08:59 pm
Just struggling with this question any help would be appreciated

This definitely looks like a tough one! Let's take a look at the bottom triangle, and see if we can get anything out.

Firstly, let's label the height of each telegraph pole (since they're the same!) 'h'. Now, we know that



Rearranging,



Great! So, both telegraph poles are height 20m. Now, we can use the sin rule to find AD. We know that



Solving for AD gives us

Title: Re: General Math Q+A Thread
Post by: damecj on March 26, 2017, 09:48:12 am
This definitely looks like a tough one! Let's take a look at the bottom triangle, and see if we can get anything out.

Firstly, let's label the height of each telegraph pole (since they're the same!) 'h'. Now, we know that



Rearranging,



Great! So, both telegraph poles are height 20m. Now, we can use the sin rule to find AD. We know that



Solving for AD gives us




Awesome thanks heaps, was thinking had to do something like that just overcomplicated it.
Title: Re: General Math Q+A Thread
Post by: sophroberts812 on March 26, 2017, 10:54:04 am
Hi guys, I always seem to get probability questions wrong so would someone be able to give any tips on how to understand the wording of questions (like the one below), or if there's a cheat way to always get the right answer? haha thank you!!!


oh and also the second probability question is something i never learnt because I was away in year 10 when it was taught and didn't do prelim general, so if you could also explain how to do these questions that'd be much appreciated!!  ;)

THANK YOU!!
Title: Re: General Math Q+A Thread
Post by: jakesilove on March 26, 2017, 11:13:33 am
Hi guys, I always seem to get probability questions wrong so would someone be able to give any tips on how to understand the wording of questions (like the one below), or if there's a cheat way to always get the right answer? haha thank you!!!


oh and also the second probability question is something i never learnt because I was away in year 10 when it was taught and didn't do prelim general, so if you could also explain how to do these questions that'd be much appreciated!!  ;)

THANK YOU!!

Hey! Probability questions are always really tough, so to be honest my only advice is to do loads of practice. I did 4U maths, but still found this sort of probability really hard, particularly just understanding what the hell the question was actually asking. By doing loads of questions, and looking at the answers when you get stuck, you start to get a feel for when you should be using certain techniques.

Now, let's look at the first question. Clearly, the unknown value will be 12 (the total) - 4 (predicted success/actual failure) = 8 (predicted failure/actual failure).

Now, if a business is chosen at random, what is the probability that it succeeded? This is completely detached from the predictions, so we just look at the total business, and their actual failures/success. There are 50 total businesses, 38 of them succeeded, and 12 of them failed. So, the probabilities will be




Okay, now the last part is the most difficult. If she predicted success, what is the likely hood that the business actually succeeded?

Well, if she predicted success, 28 of them succeeded and 4 of them failed. So, the probability is just




As it will just be the number of successes, over the total number! That wasn't actually so bad, but understanding the table was tricky.

Now, let's look at the second question. Because the letter 'S' MUST be at the start, we ignore that fact (ie. there's a 100% probability that it starts with S, so we don't really care about the letter anymore). The rest of the digits (four) can be any of 10 numbers.

We think about this in steps. Ie. How many ways could we choose the first number? How many ways could we choose the second number? How many ways could we choose the third number? How many ways could we choose the fourth number? Then, we simply multiply them together to get the total ways.

Each time we choose a number, there will be 10 numbers to choose from. So, each of the steps will have 10 choices, and the answer will be D (10*10*10*10). Easy!

The question could have been a little more complicated, though. Let's say you couldn't repeat the same number twice (ie. If I chose a 3 the first time, I couldn't choose a 3 for any other number).

First, we would have 10 choices. Then, we would have 9 choices (as one cannot be reused, which is whatever we chose the first time). Then, we have 8 choices. Then, we have 7 choices. So, our answer would be 10*9*8*7. This is just an example of how these questions commonly work.

Hope all of this makes sense!
Title: Re: General Math Q+A Thread
Post by: emilybrooks99 on March 27, 2017, 01:08:40 pm
We've gotten our half yearly maths exams back and in the exam this one completely stumped me for some reason. Can anyone work me through how to get the answer? (which was C btw)(http://uploads.tapatalk-cdn.com/20170326/411df48e26fd5c84bcd2002d094f536f.jpg)
Title: General Math Q+A Thread
Post by: RuiAce on March 27, 2017, 01:18:18 pm


Note that the square then gets chucked into both terms to get what you want in C
Title: Re: General Math Q+A Thread
Post by: emilybrooks99 on March 27, 2017, 01:32:08 pm
Another question I got stuck with in my maths exam is this one below. Can anyone explain what the answer is and how to get it? (http://uploads.tapatalk-cdn.com/20170326/a873d144201188ec34867cb75e16d642.jpg) thanks!
Title: Re: General Math Q+A Thread
Post by: Neilab on March 27, 2017, 02:23:27 pm
What is the best way to manage time in exams?
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on March 27, 2017, 02:24:52 pm
Another question I got stuck with in my maths exam is this one below. Can anyone explain what the answer is and how to get it? (http://uploads.tapatalk-cdn.com/20170326/a873d144201188ec34867cb75e16d642.jpg) thanks!

Sure! So the measure of kWh is really just a measure of time spent using the device. For example, the price of 12.5 cents per kWh. If we use a 1W device for an hour, we'd use 1kWh and it would cost 12.5 cents.

Here, we use the kettle 10 minutes a day (4 times 2.5 minutes). That is \(10\times365=3650\) minutes per year, which is \(3650\div60=60.83\) hours per year. The device is rated for 1800W. So, the final answer is obtained by multiplying the W of the device, with the time it is active to get Wh:



Dividing this by 1000 to get kWh:



Then multiplying by a price of $0.125:



So the answer is C (I'm not sure why it said nearest 50 cents though, because that would be $13.50?) :)
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on March 27, 2017, 02:28:55 pm
What is the best way to manage time in exams?

Hey! I think it depends a lot on your personal style - Some people will like to spend more time on the hard stuff first. Some people will want the easy stuff out of the way. You need to figure out what works for you - The only golden rule is to never get stuck on one question for more than a minute, you can always come back for it! :)
Title: Re: General Math Q+A Thread
Post by: olr1999 on April 18, 2017, 03:18:03 pm
Hi! Just wondering how to do question 5c and 6i in the attachment. Thanks!
Title: Re: General Math Q+A Thread
Post by: RuiAce on April 19, 2017, 08:29:53 am
Hi! Just wondering how to do question 5c and 6i in the attachment. Thanks!


Note: When I submitted the values into R (programming language) it told me that the lower quartile is actually 62.75. I'm not too sure why as I haven't had to do stem-and-leaf plots by hand in a while. It doesn't affect the final answer, but it could mess up working out.

Title: Re: General Math Q+A Thread
Post by: olr1999 on April 23, 2017, 01:49:46 pm


Note: When I submitted the values into R (programming language) it told me that the lower quartile is actually 62.75. I'm not too sure why as I haven't had to do stem-and-leaf plots by hand in a while. It doesn't affect the final answer, but it could mess up working out.



I would have thought so too! But in actual fact (and I should have mentioned this before), the answer for question 5c is 30% for both data sets. Not sure how this answer was reached as the answers do not provide working out ...
Title: Re: General Math Q+A Thread
Post by: RuiAce on April 23, 2017, 02:04:40 pm
I would have thought so too! But in actual fact (and I should have mentioned this before), the answer for question 5c is 30% for both data sets. Not sure how this answer was reached as the answers do not provide working out ...
There's 16 numbers and 16 is divisible by 4 so I don't see how that works. Just in case I'm missing something in general maths I'll ask for some confirmation/correction
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on April 23, 2017, 02:15:52 pm
I would have thought so too! But in actual fact (and I should have mentioned this before), the answer for question 5c is 30% for both data sets. Not sure how this answer was reached as the answers do not provide working out ...

Hey! I'm with Rui, I don't get that answer of 30% - By definition each quartile represents 25% of your data, so the upper and lower quartiles should encompass 50% in both cases! :) it could be that the answer is incorrect? :)
Title: Re: General Math Q+A Thread
Post by: olr1999 on April 23, 2017, 04:27:26 pm
Hey! I'm with Rui, I don't get that answer of 30% - By definition each quartile represents 25% of your data, so the upper and lower quartiles should encompass 50% in both cases! :) it could be that the answer is incorrect? :)

I agree with both of you, I'm not sure how it works either but I think it means something different to how it sounds. The answer for question 6i is also different to what is expected (The answers say 56.25% for boys and 64% for girls)... I'll have to take it up with my maths teacher! Thanks anyway :)
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on April 23, 2017, 05:15:56 pm

I agree with both of you, I'm not sure how it works either but I think it means something different to how it sounds. The answer for question 6i is also different to what is expected (The answers say 56.25% for boys and 64% for girls)... I'll have to take it up with my maths teacher! Thanks anyway :)

Yeah I'm thinking we are misinterpreting the question somehow, let us know how you go!
Title: Re: General Math Q+A Thread
Post by: tahliamag on May 15, 2017, 10:35:34 am
hey guys!
This is more a general question but does anyone have any tips on how to revise for prelim and hsc content at the same time? Thanks in advance!

Hi guys,
Does anyone have any tips on how to approach studying for multipe choice questions for exams? It's something I struggle with, thankyou!


Moderator action: Posts merged. At times like this, please resort to editing your post instead of posting consecutively.

Title: Re: General Math Q+A Thread
Post by: olr1999 on May 15, 2017, 11:15:58 am
Yeah I'm thinking we are misinterpreting the question somehow, let us know how you go!

My maths teacher was also stumped! I guess we will just assume the answer given was a mistake...
Title: Re: General Math Q+A Thread
Post by: Jess.martinuzzo on May 15, 2017, 08:01:40 pm
Hey guys,
Hope someone can help me, just doing a bit of maths homework and I'm struggling to figure out how to do this probability question.

'In Poker, a 'royal flush' is getting 10, J, Q, K and A of the same suit. Show that there is 1 chance in 649 740 of achieving this.'

please help!!  ;D ;D ;D
Title: Re: General Math Q+A Thread
Post by: RuiAce on May 15, 2017, 08:13:21 pm
hey guys!
This is more a general question but does anyone have any tips on how to revise for prelim and hsc content at the same time? Thanks in advance!

Hi guys,
Does anyone have any tips on how to approach studying for multipe choice questions for exams? It's something I struggle with, thankyou!


Moderator action: Posts merged. At times like this, please resort to editing your post instead of posting consecutively.
20% of the final exam is based off preliminary content. That should give you a rough indication on how to study for it.

The main focus until the trials will still be HSC content so you should be well aware of what to focus on. Come HSC time, you may employ various strategies to ensure you have preliminary content covered, e.g. getting it back in your head first before everything else, adding bits and pieces of in as you study HSC content etc. It is all about time management at the end of the day.

You can only study by practicing. If there are specific areas of concern in multiple choice you may bring them up, but there is no better advice than keep practicing.
My maths teacher was also stumped! I guess we will just assume the answer given was a mistake...
It has to be a mistake then for sure.
Hey guys,
Hope someone can help me, just doing a bit of maths homework and I'm struggling to figure out how to do this probability question.

'In Poker, a 'royal flush' is getting 10, J, Q, K and A of the same suit. Show that there is 1 chance in 649 740 of achieving this.'

please help!!  ;D ;D ;D





Title: Re: General Math Q+A Thread
Post by: Jess.martinuzzo on May 15, 2017, 08:22:04 pm
{Jokers are conventionally excluded in Poker.}[/tex]





[/quote]

Ahh thankyou so much! So essentially its: 52 x 51 x 50 x 49 x 48 over 5 factorial? Then with the 4 favourable outcomes over 2 598 960, which simplifies to the answer, 1/649 740?
Title: Re: General Math Q+A Thread
Post by: RuiAce on May 15, 2017, 08:22:58 pm
{Jokers are conventionally excluded in Poker.}[/tex]







Ahh thankyou so much! So essentially its: 52 x 51 x 50 x 49 x 48 over 5 factorial? Then with the 4 favourable outcomes over 2 598 960, which simplifies to the answer, 1/649 740?

Yep;
Title: Re: General Math Q+A Thread
Post by: natasha.rh on May 24, 2017, 02:18:16 pm
hi,
does anyone have any past papers on the focus study: health and mathematics?
much appreciated!
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on May 24, 2017, 02:52:25 pm
hi,
does anyone have any past papers on the focus study: health and mathematics?
much appreciated!

Hey! It might be worth having a bit of a look in this collection - There's heaps there, I'm not sure if any of it will be for this Focus Study but worth a shot! ;D
Title: Re: General Math Q+A Thread
Post by: natasha.rh on May 24, 2017, 03:38:54 pm
Hey! It might be worth having a bit of a look in this collection - There's heaps there, I'm not sure if any of it will be for this Focus Study but worth a shot! ;D
so many papers! thank you so much!!!
Title: Re: General Math Q+A Thread
Post by: Lachlan Morley on May 29, 2017, 05:55:25 pm
Hi all,
This question is in regard to un ordered and ordered selections

When a question states how many possible selections are able to occur, is it unordered or order, I always thought that unordered in the question needed to state " How many diffrent possible selections" as that is what takes the double ups out
Title: Re: General Math Q+A Thread
Post by: RuiAce on May 29, 2017, 06:02:56 pm
Hi all,
This question is in regard to un ordered and ordered selections

When a question states how many possible selections are able to occur, is it unordered or order, I always thought that unordered in the question needed to state " How many diffrent possible selections" as that is what takes the double ups out
Sometimes it can be inferred from the question whether you should treat it as ordered are unordered. The wording of the question may imply that common sense should be used.

But that being said I didn't do general either. Could I please see the question(s) involved that lead to this query?
Title: Re: General Math Q+A Thread
Post by: Lachlan Morley on May 30, 2017, 12:20:19 pm

Sometimes it can be inferred from the question whether you should treat it as ordered are unordered. The wording of the question may imply that common sense should be used.

But that being said I didn't do general either. Could I please see the question(s) involved that lead to this query?

The question was of 15 Basketball players, 4 were selected for the team . How many possible ways can these individual be selected

I was always taught that how many possible ways meant that you include all the double ups as whilst they are including the same players , they express it in a different way so there fore is a different way of doing it therefore not dividing by factorial. If the question said how many different possible ways it would obviously mean to divide by the factorial although the question docent ask the different ways it asks how many possible ways so I'm under the assumption that I don't divide by the factorial as that wouldn't be answering the question
Title: Re: General Math Q+A Thread
Post by: RuiAce on May 30, 2017, 12:28:36 pm
I don't necessarily agree with that convention. That's pretty restricting on what makes intuitive sense.

For this particular problem, the way I see it is that if persons A B C and D made the team, then this would be equivalent to saying persons D C B and A made it. There isn't a ranking or hierarchy system here or something, there's just one single team with four members. This implies that repetition of cases does exist, and that I do need to divide by the factorial here.

If, for example, I had to choose positions specifically (e.g. center, forward), then I would not divide by 4!.

The important thing to realise is that division by the factorial is for an unordered selection, which is what we have here. If we have an ordered selection, then we should definitely not divide.
Title: Re: General Math Q+A Thread
Post by: amorphous on June 06, 2017, 11:45:15 am
Hi guys! I have math question I'm stuck on, can someone please help me? Thank you.

It takes one man one day to dig a 4m x 4m x 4m hole. How long does it take 4 men working at the same rate to dig 16m x 16m x 16m hole?
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on June 06, 2017, 12:04:34 pm

Hi guys! I have math question I'm stuck on, can someone please help me? Thank you.

It takes one man one day to dig a 4m x 4m x 4m hole. How long does it take 4 men working at the same rate to dig 16m x 16m x 16m hole?

Hey! So one man can dig out a volume of 4x4x4=64 cubic metres per day. 4 men, therefore, can dig out quadruple that - 64x4=256 cubic metres, per day.

Now, the hole we are digging is 16x16x16=4096 cubic metres. To get our answer, we just go 4096/256=16 days! Does that make sense?
Title: Re: General Math Q+A Thread
Post by: MisterNeo on June 06, 2017, 12:08:49 pm
Hi guys! I have math question I'm stuck on, can someone please help me? Thank you.

It takes one man one day to dig a 4m x 4m x 4m hole. How long does it take 4 men working at the same rate to dig 16m x 16m x 16m hole?

Hi! The answer is 16 days.


Divide 4096 by 256.
Hence, 16 days!
Title: Re: General Math Q+A Thread
Post by: Kirri Rule on June 06, 2017, 07:55:30 pm
Hi sorry we have a maths exam coming up next week on only 4 specific topics and was wondering if anyone knew where to find papers or questions that are releated to specific topics.( As I have already done all the past HSC and textbook questions.) Thank you
Title: Re: General Math Q+A Thread
Post by: RuiAce on June 06, 2017, 08:01:19 pm
Hi sorry we have a maths exam coming up next week on only 4 specific topics and was wondering if anyone knew where to find papers or questions that are releated to specific topics.( As I have already done all the past HSC and textbook questions.) Thank you
It is honestly not a bad idea to pluck out only the relevant past papers out of trials and just do them

The website may have some other useful things though.
Title: Re: General Math Q+A Thread
Post by: Kirri Rule on June 06, 2017, 08:05:30 pm
It is honestly not a bad idea to pluck out only the relevant past papers out of trials and just do them

The website may have some other useful things though.
I know sometimes in the HSC and Trial questions there are like the questions that have hidden underlying topics like the capture recapture questions, how should we look at the question to see what topic its from? Thanks
Title: Re: General Math Q+A Thread
Post by: RuiAce on June 06, 2017, 08:10:59 pm
The line might be blurrier for general maths comparatively speaking with the other courses but you should have a solid idea of which topics are from where. Some will speak out to you which topic they're from because they only require one thing.

If you can guarantee that you reach a point where you know it won't be in the exam, go ahead and just look at the answers to confirm your instinct.

Essentially, if a question looks as though it involves concepts in the topics you're being examined on you should never disregard it. You can only jump when you're positive it's safe to. I personally don't advise it (because why should you when you can prepare for the trials a bit as well) but if you're in time pressure with studying that's what I'd say.
Title: Re: General Math Q+A Thread
Post by: samsclaire on June 13, 2017, 06:00:23 pm
hey! can someone please explain trig with obtuse angles? (i really don't get how it works)
Title: Re: General Math Q+A Thread
Post by: S200 on June 13, 2017, 06:01:22 pm
Got an example question??
Title: Re: General Math Q+A Thread
Post by: jakesilove on June 13, 2017, 06:11:19 pm
hey! can someone please explain trig with obtuse angles? (i really don't get how it works)

Hey! I didn't do General, but I'm using your formula sheet as a guide. Let's look at the following triangle
(http://images.tutorvista.com/cms/images/67/area-for-obtuse-triangle.png)
We denote capital letters as the angle, and small letters as the side. There are a few formulas you need to know
Area

First, you need to be able to find the area of this triangle. To do this, we simply apply the formula

Note that the angle, C, needs to be between the two sides a and b. So, in the above triangle, the formula would actually be

You only need to know one angle, and the two sides surrounding that angle, to get the area!



The sine rule states that the ratio of the sine of an angle over the opposite side is the same as the ratio of the sine of any other angle over their opposite sides. On your formula sheet, it is

In our above triangle, it will be


Note that it's all about the ANGLE and it's OPPOSITE side! Here, you can use two known angles and a known side to find other sides, or two known sides and one known angle to find another angle.

Cosine rule

Finally, we have the cosine rule, which is used to find angles or sides given known values. On your formula sheet, the rule is

(http://i.imgur.com/rxJEjMa.png)


Give us some example questions we can help you with! It'll be way easier to understand when you're applying it :)

Title: Re: General Math Q+A Thread
Post by: Lachlan Morley on June 16, 2017, 07:54:22 pm
Does anyone have any tips to ensure that silly mistake in exams are eradicated, normally I know how to do the question although i miss out a key part of the question
Title: Re: General Math Q+A Thread
Post by: RuiAce on June 16, 2017, 08:05:23 pm
Does anyone have any tips to ensure that silly mistake in exams are eradicated, normally I know how to do the question although i miss out a key part of the question
Eradicating it is hard. People that eradicate silly mistakes are the ones that get state ranks.

Of course, that's definitely possible. But setting goals that high is asking quite far. Let's think about how you can minimise it. In the HSC, you're allowed to take a highlighter in with you. You can use this to your advantage in one of two ways:
- Highlight everything that's likely to important, and preferably use two highlighters so you can contrast between the two. This will definitely include numbers and any variables given.
- Highlight things as they get used, and consider when and how you used them.
As usual, underlining is a substitute if you can make it effective.

Read the question twice. Scan the text to know what's going on (and look at diagrams/tables given at the same time to relate what you read). Look out for some key words like tax, interquartile range etc.

The examiners aren't going to look at your multiple choice question booklet. You can use that as scrap paper. You can list out the things you're looking for as you're going through the questions. (Of course, can understand why this might be time consuming.)

There's quite a ton of topics in maths, so in your free time it may help to list out where the silly mistakes tend to be within specific topics. Then, when doing past papers and what not, have those lists out in front of you so you can check to see what you might miss out on. Same goes for questions in general (e.g. misreading a key word). Having a list of silly mistakes out in front of you and being able to check it as you're studying will help you ensure that you won't make such mistakes on the day.
Title: Re: General Math Q+A Thread
Post by: sageziman on June 17, 2017, 08:51:36 am
Would anyone be able to break down the working out for 10 b and c for me please :)
Title: Re: General Math Q+A Thread
Post by: RuiAce on June 17, 2017, 11:24:11 am

Would anyone be able to break down the working out for 10 b and c for me please :)
To ensure that we have exactly one ace, we put that in first. Note that there are 4 aces, so we have 4 possible outcomes.

For the other cards, treat it like part a) except we only have 48 cards and not 52 to consider now. Remember, we don't want any more aces.
Similar to part a), I.e. Factoring in repetition, we have 48*47*46*45/4!

So the answer is 4*48*47*46*45/4!

Part c is similar but there's repetition in the aces as well because now we want exactly two aces. I leave you to think about why the answer is 4*3/2! times 48*47*46/3! using a similar analysis
Title: Re: General Math Q+A Thread
Post by: lilmisshemingway on June 18, 2017, 12:10:42 pm
Hi anyone/everyone!
I just got a sighted task back for General Maths and I failed. Like, really badly failed. I've had a 45-50% average for this subject this entire year, and I've been a little slack on homework because of competing priorities and math tends to get pushed to the side because of my 4u Major Work. I've always had a really negative mindset surrounding maths-- and I'm on 11 units so I can't drop, and half of it is going to count towards my ATAR whether I like it or not.
So is it possible that I can still pick up my marks for trials and HSC? I really don't want to end up with a Band 3.  :-[ :-[
Title: Re: General Math Q+A Thread
Post by: S200 on June 19, 2017, 09:47:23 pm
Hi anyone/everyone!
I just got a sighted task back for General Maths and I failed. Like, really badly failed. I've had a 45-50% average for this subject this entire year, and I've been a little slack on homework because of competing priorities and math tends to get pushed to the side because of my 4u Major Work. I've always had a really negative mindset surrounding maths-- and I'm on 11 units so I can't drop, and half of it is going to count towards my ATAR whether I like it or not.
So is it possible that I can still pick up my marks for trials and HSC? I really don't want to end up with a Band 3.  :-[ :-[

Hey there!!
You think THAT's a fail??
My teacher told me last week, just before my exam, that I had failed my re-sit of my Methods Sac... so thats an N for the semester...
Other than moral support, my only advice I can give is the same as I'm doing right now...
Bed @ 10, awake at 4.30, get onto the homework!!
Catch up or else!! :D

"The good thing about hitting rock bottom??... There's only one way you can go!! And thats UP!!!
Title: Re: General Math Q+A Thread
Post by: emilybrooks99 on June 22, 2017, 07:47:14 pm
I've got my maths trial exam tomorrow and I'm doing last minute revision and review tests from my textbook. Can anyone help me with getting the answers for 14 and 15 cause nothing I seem to do matches up with the answers in the back of the book

(http://uploads.tapatalk-cdn.com/20170622/8bf5d4d9ea9eb09661b7ff1742c2f2c0.jpg)
Title: Re: General Math Q+A Thread
Post by: RuiAce on June 22, 2017, 07:50:43 pm
I've got my maths trial exam tomorrow and I'm doing last minute revision and review tests from my textbook. Can anyone help me with getting the answers for 14 and 15 cause nothing I seem to do matches up with the answers in the back of the book

(http://uploads.tapatalk-cdn.com/20170622/8bf5d4d9ea9eb09661b7ff1742c2f2c0.jpg)


____________________________



Divide to get C.
Title: Re: General Math Q+A Thread
Post by: olr1999 on July 14, 2017, 04:38:19 pm
Best way to pick up silly mistakes?
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on July 14, 2017, 10:03:21 pm
Best way to pick up silly mistakes?

Hey! Didn't do General, but I feel like spotting mistakes works the same at any level of Maths study! You'll want to make sure you are moving slowly through the exam (within reason of course). Highlight key terms, put things into your calculator properly and carefully - Try to avoid making the mistake in the first place. Beyond that, to pick up a silly mistake you need to know the ones you usually make. Are you likely to make a mistake in algebra? Try double checking algebra working in the last five minutes. Screw up the interest rate in Credit Card questions? Take 30 seconds to check yourself before you move on from those questions.

You know the saying, "Know your enemy?" That's exactly my advice here ;D
Title: Re: General Math Q+A Thread
Post by: olr1999 on July 15, 2017, 09:50:43 am
Hey! Didn't do General, but I feel like spotting mistakes works the same at any level of Maths study! You'll want to make sure you are moving slowly through the exam (within reason of course). Highlight key terms, put things into your calculator properly and carefully - Try to avoid making the mistake in the first place. Beyond that, to pick up a silly mistake you need to know the ones you usually make. Are you likely to make a mistake in algebra? Try double checking algebra working in the last five minutes. Screw up the interest rate in Credit Card questions? Take 30 seconds to check yourself before you move on from those questions.

You know the saying, "Know your enemy?" That's exactly my advice here ;D

Awesome! Thanks so much :)
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on July 15, 2017, 12:03:36 pm
Hi all

So I am currently prepping for my general maths exam and am stuck on this question. Any help would be appreciated.

Josephine invested $1000 at the end of each year for five years. Her investment earned interest at 4.8% per annum compounded annually. What was the total of Jospehine's investment (to the nearest dollar) at the end of the fifth year?

Thanks  :)
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 15, 2017, 12:21:46 pm

Hi all

So I am currently prepping for my general maths exam and am stuck on this question. Any help would be appreciated.

Josephine invested $1000 at the end of each year for five years. Her investment earned interest at 4.8% per annum compounded annually. What was the total of Jospehine's investment (to the nearest dollar) at the end of the fifth year?

Thanks  :)
Did this question come from a paper prior to the syllabus change in 2014? Back then they had a formula to handle the value of an annuity, but it has since been scrapped.
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on July 15, 2017, 02:24:00 pm
Did this question come from a paper prior to the syllabus change in 2014? Back then they had a formula to handle the value of an annuity, but it has since been scrapped.

Yes it has come from a past paper from 2001, but was unsure of whether this was something I needed to know. So is this something i should not worry about or is there now a new way to work it out?
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 15, 2017, 02:28:50 pm


_____________________



Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on July 15, 2017, 02:36:24 pm
Yes it has come from a past paper from 2001, but was unsure of whether this was something I needed to know. So is this something i should not worry about or is there now a new way to work it out?

Just to clarify, although you could use Rui's method above, you'd never be asked to do it in an exam like that - No stress!! Always tough to know with old papers so glad you asked ;D
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on July 15, 2017, 04:39:29 pm
thank you guys so so much I was really struggling so your help is so appreciated! I will be posting way more questions later   ;) ;)
but thanks again for the amazing help !!  ;D ;D ;D
Title: Re: General Math Q+A Thread
Post by: gaudy on July 15, 2017, 05:06:52 pm
QUESTION:
The hsc marks for a particular course are normally distributed with a mean of 65 and a standard deviation of 8.
What percentage of results lie between 65 and 73?

pls help
Title: Re: General Math Q+A Thread
Post by: jakesilove on July 15, 2017, 05:37:42 pm
QUESTION:
The hsc marks for a particular course are normally distributed with a mean of 65 and a standard deviation of 8.
What percentage of results lie between 65 and 73?

pls help

Hey! On your formula sheet, it says 'Approximately 68% of scores have z-scores between -1 and 1". This means that, one standard deviation away from the medium to either side contains 68% of the results! However the question only is interested in those scores ABOVE the medium, not to either side. So, we divide the percentage of scores by two, getting 34% as our answer :)

Jake
Title: Re: General Math Q+A Thread
Post by: Potatohater on July 17, 2017, 09:20:28 am
Hey, how would I go about solving this question?
Mary is designing a website that requires unique login generation. She plans to generate logins using 2 capital letters followed by a series of numerals 0-9 inclusive, all logins have the same number of numerals, repitition is allowed, what is the minimum number of numerals needed for each login so that Mary can generate at least 3 million logins?
Title: Re: General Math Q+A Thread
Post by: stephanieazzopardi on July 17, 2017, 09:43:24 am
Hey, how would I go about solving this question?
Mary is designing a website that requires unique login generation. She plans to generate logins using 2 capital letters followed by a series of numerals 0-9 inclusive, all logins have the same number of numerals, repitition is allowed, what is the minimum number of numerals needed for each login so that Mary can generate at least 3 million logins?

Hi Potatohater,

I think this is a case of guess and check. So the first two items of her password are 2 letters. So the number of possible combinations would equal 26 x 26. To work out how many numerals she would need to have in her password to generate at least 3 million logins, you would just type 26 x 26 x 10 x 10 x 10 etc, and see how many sets of x 10 you had in your calculation before you reached at least 3 million, each x 10 representing a numeral.

So if we do 26 x 26 x 10 x 10 x 10 (3 numerals), we get 676 000 = not at least 3 million, right?
So let's do 26 x 26 x 10 x 10 x 10 x 10 (4 numerals). We get 6 760 000 = at least 3 million.

So the answer should be 4. Hope that helps! Let us know if you have any more questions :)
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 17, 2017, 09:52:44 am
Remark: It's doable with logs but I doubt that's in general so I'd vouch for guess and check as well
Title: Re: General Math Q+A Thread
Post by: stephanieazzopardi on July 17, 2017, 10:11:30 am
Remark: It's doable with logs but I doubt that's in general so I'd vouch for guess and check as well

No logs in General :)
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on July 18, 2017, 08:57:09 pm
hey guys
So i am doing a past trial paper and got stuck on this question.

It has worked solutions as seen in the picture but I still don't understand how each step was reached.. if that makes sense?
I just need some help understanding the question or if there is a simpler way to do this question let me know please! :)
Title: Re: General Math Q+A Thread
Post by: Shadowxo on July 18, 2017, 09:14:39 pm
hey guys
So i am doing a past trial paper and got stuck on this question.

It has worked solutions as seen in the picture but I still don't understand how each step was reached.. if that makes sense?
I just need some help understanding the question or if there is a simpler way to do this question let me know please! :)


This is using the cosine rule
a2=b2+c2+2bc cosA
a = BC, b = AC c= AB
Or in other words a= 90, b = c = x
A= 113ş
That's how they get the first line
From there they just rearrange it. They get all the terms with x on one side (they already are though), all the terms without on another, then they factor out the x2, get x2 as the subject then square root both sides

If you're unsure about the cosine rule, you should brush up on it (don't know what's required for your course though) and if you still need help let me know. Rest is just rearranging the equation to make x the subject
Title: Re: General Math Q+A Thread
Post by: Potatohater on July 19, 2017, 07:05:48 pm
Hey, so I tried this question 2 different ways so far and none of them have worked, so how should I go about this question:
2 cities lie on the same line of longitude and are 4356km apart. One city is located 47 degrees north, what is the latitude of the 2nd city if it is south of the 1st?
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 19, 2017, 07:19:39 pm
Hey, so I tried this question 2 different ways so far and none of them have worked, so how should I go about this question:
2 cities lie on the same line of longitude and are 4356km apart. One city is located 47 degrees north, what is the latitude of the 2nd city if it is south of the 1st?
I'm not entirely confident of this method (mostly because I didn't actually do general maths), but I believe you should use the arc length formula \(l=\frac{\theta}{360}2\pi r\) (from the formula sheet) to figure out the angle between the two cities. Note that \(l=4356\), and of course \(r=6400 \)

Then, you know that the first city is at 47 degrees N. So subtract whatever \(\theta\) was from 47 N to find the latitude of the second city.
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on July 19, 2017, 07:29:27 pm
This is using the cosine rule
a2=b2+c2+2bc cosA
a = BC, b = AC c= AB
Or in other words a= 90, b = c = x
A= 113ş
That's how they get the first line
From there they just rearrange it. They get all the terms with x on one side (they already are though), all the terms without on another, then they factor out the x2, get x2 as the subject then square root both sides

If you're unsure about the cosine rule, you should brush up on it (don't know what's required for your course though) and if you still need help let me know. Rest is just rearranging the equation to make x the subject


The part where I got confused was where there was 2x squared - 2x squared which in the following line became only one 2x squared and a one in the bracket.
Where did the one come from and since they were like terms would those 2x's minus each other and equal 0?
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 19, 2017, 07:31:50 pm

The part where I got confused was where there was 2x squared - 2x squared which in the following line became only one 2x squared and a one in the bracket.
Where did the one come from and since they were like terms would those 2x's minus each other and equal 0?
They factorised \(2x^2\) out.
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on July 19, 2017, 07:49:40 pm

They factorised \(2x^2\) out.


i know i am going to sound like a pain but could you break down the steps as to how they factorised the 2x squared in the equation for the triangle previously. like I understand they factorised it but I would like it to be broken down so I get a clearer understanding
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 19, 2017, 07:49:47 pm


Title: Re: General Math Q+A Thread
Post by: morning_sunshine on July 19, 2017, 07:57:36 pm




OMG IT ALL MAKES SENSE!
If I was in an exam though, how would i know that i had to factorise the equation
(I'm super dumb so I really need all the help I can get)
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 19, 2017, 08:05:01 pm
OMG IT ALL MAKES SENSE!
If I was in an exam though, how would i know that i had to factorise the equation
(I'm super dumb so I really need all the help I can get)
Given that ultimately we had to make \(x\) the subject, it makes sense to isolate \(x\) first. But in that example, we'd have to isolate \(x^2\) as if we factor out just \(x\), we'd only end up factoring it out again.

So we pull out the \(x^2\), and then we pull the 2 out just because it's a common factor. You need to be capable at spotting common factors, as they're the biggest hint to factorise in a rearranging question.

It's also important to look at what you're trying to aim for. If you didn't realise you had to make \(x\) the subject, you wouldn't be able to spot anything.
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on July 19, 2017, 08:13:00 pm
Given that ultimately we had to make \(x\) the subject, it makes sense to isolate \(x\) first. But in that example, we'd have to isolate \(x^2\) as if we factor out just \(x\), we'd only end up factoring it out again.

So we pull out the \(x^2\), and then we pull the 2 out just because it's a common factor. You need to be capable at spotting common factors, as they're the biggest hint to factorise in a rearranging question.

It's also important to look at what you're trying to aim for. If you didn't realise you had to make \(x\) the subject, you wouldn't be able to spot anything.

Thank you so so much!
Final question I promise :)
So how do I get that 2x squared onto the other side?
Would I multiply it on both sides and then move the 90 across?
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 19, 2017, 08:18:41 pm

Title: Re: General Math Q+A Thread
Post by: jadzia26 on July 19, 2017, 10:20:02 pm
Hey, any suggestions on how to beat silly mistakes?
Although math is one of my strongest subjects i find the really wordy questions throw me and i end up messing up completely and only afterwards ill realise how simple it was. its super frustrating that silly mistakes drag me down a bit  :-\
Title: Re: General Math Q+A Thread
Post by: Shadowxo on July 19, 2017, 10:24:12 pm
Hey, any suggestions on how to beat silly mistakes?
Although math is one of my strongest subjects i find the really wordy questions throw me and i end up messing up completely and only afterwards ill realise how simple it was. its super frustrating that silly mistakes drag me down a bit  :-\

Wordy questions can be quite confusing. For worded questions I tend to write down the important information (eg a truck is travelling along a road that is of a length of 20km, I'd write "L=20km"). I'd summarise all the information like this to make it easier to process all the information and see if any formulas would apply.
My tip of the day. I still struggle with silly mistakes though, everyone does so don't worry, you're not alone :)
Title: Re: General Math Q+A Thread
Post by: jadzia26 on July 19, 2017, 11:06:59 pm
Whenever I do math papers I always keep the formula sheet next to me!
I find that knowing which parts of the syllabus i need to know and which parts are given to me helps so much and releases stress that just isn't necessary! :)
Title: Re: General Math Q+A Thread
Post by: Potatohater on July 22, 2017, 11:56:58 am
How do you go about solving 6w^4 X 1/2w^2? I'm having trouble knowing what index law to apply to this
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on July 22, 2017, 11:59:29 am
How do you go about solving 6w^4 X 1/2w^2? I'm having trouble knowing what index law to apply to this

Hey! This is the index law for multiplication, remember:



The constants will be multiplied together separately, and then we use the index law above for the pro-numeral:



Does this make sense? :)
Title: Re: General Math Q+A Thread
Post by: katie,rinos on July 22, 2017, 04:14:58 pm
Hey Guys,
I've brought the topic tests book for general maths and was wondering if there was a time limit that we should be using for the tests?
Thanks heaps :)
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on July 22, 2017, 04:35:34 pm
Hey Guys,
I've brought the topic tests book for general maths and was wondering if there was a time limit that we should be using for the tests?
Thanks heaps :)

Hey Katie! The tests are designed to be done in an hour, but if it ends up being too hard or easy feel free to adjust - Use a time limit that is challenging but still achievable for you, and don't be afraid to make your time limits shorter as you go on :)
Title: Re: General Math Q+A Thread
Post by: Lachlan Morley on July 22, 2017, 06:12:12 pm
Anyone know how to asess CSSA General Maths trial papers
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 22, 2017, 06:13:37 pm
Anyone know how to asess CSSA General Maths trial papers
CSSA papers are copyrighted and legal distribution of it is not permitted. It is also therefore not on the forums.
Title: Re: General Math Q+A Thread
Post by: vanessa mbogo on July 22, 2017, 07:30:56 pm
please help
what amount must be invested now at 4% per annum ,compounded quarterly ,so that in five years it will have grown to $60000
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 22, 2017, 07:32:56 pm
please help
what amount must be invested now at 4% per annum ,compounded quarterly ,so that in five years it will have grown to $60000



Divide by that power and plug into the calculator.
Title: Re: General Math Q+A Thread
Post by: Potatohater on July 23, 2017, 06:10:51 am
Hey! This is the index law for multiplication, remember:



The constants will be multiplied together separately, and then we use the index law above for the pro-numeral:



Does this make sense? :)

Yes that makes sense, thanks
Title: Re: General Math Q+A Thread
Post by: Turtlebae on July 24, 2017, 12:12:07 am
I don't know what is a stamp duty is can someone please help me on answering question I) & ii)

a) Lisa buys a car which has a market value of $60 000 before on-road costs. Stamp duty on the car is calculated at these rates:

• 3% of the market value to and including $45 000
• 5% of the market value over $45 000

I) calculate the stamp duty payable on the purchase of the car

ii) The car depreciates at a rate of 4.5% pa.  what's is the value of the car 3 years after Lisa buys it?

Title: Re: General Math Q+A Thread
Post by: jakesilove on July 24, 2017, 10:25:20 am
I don't know what is a stamp duty is can someone please help me on answering question I) & ii)

a) Lisa buys a car which has a market value of $60 000 before on-road costs. Stamp duty on the car is calculated at these rates:

• 3% of the market value to and including $45 000
• 5% of the market value over $45 000

I) calculate the stamp duty payable on the purchase of the car

ii) The car depreciates at a rate of 4.5% pa.  what's is the value of the car 3 years after Lisa buys it?



Hey! You can imagine that stamp duty is a sort of 'tax' on goods. So, let's calculate it!

We know that stamp duty is calculated at 3% up to and including $45,000, and 5% after that. So, the first $45,000 of the car will be taxed like this:



Now, the car's total cost was $60,000. So, the 'rest' of the car will be taxed ABOVE the lower rate; ie. at 5%. We've already taxed the first $45,000, leaving us with the last $15,000



So, the TOTAL tax will be



Now, the car depreciates at a rate of 4.5% pa. So, after the first year, the value goes DOWN by 4.5%



After the second year, the car goes down ANOTHER 4.5%. So, we multiply the already depreciated value again!



And, then again for a third year!



There's our answer! Hope that made sense :)
Title: Re: General Math Q+A Thread
Post by: Turtlebae on July 24, 2017, 06:27:23 pm
 
Hey! You can imagine that stamp duty is a sort of 'tax' on goods. So, let's calculate it!

We know that stamp duty is calculated at 3% up to and including $45,000, and 5% after that. So, the first $45,000 of the car will be taxed like this:



Now, the car's total cost was $60,000. So, the 'rest' of the car will be taxed ABOVE the lower rate; ie. at 5%. We've already taxed the first $45,000, leaving us with the last $15,000



So, the TOTAL tax will be



Now, the car depreciates at a rate of 4.5% pa. So, after the first year, the value goes DOWN by 4.5%



After the second year, the car goes down ANOTHER 4.5%. So, we multiply the already depreciated value again!



And, then again for a third year!



There's our answer! Hope that made sense :)


Thank you so much! And yep I understand it now :)
Title: Re: General Math Q+A Thread
Post by: vanessa mbogo on July 25, 2017, 11:28:09 pm
Zina opened an account to save for a new car. Six months after opening the account ,she made her first deposit of$ $ 1200 and continued depositing $1200 at the end of each six months period. interest was paid 3% per annum, compounded half yearly . How much was in Zina's account two years after first opening it

please help
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on July 26, 2017, 12:23:09 am
Zina opened an account to save for a new car. Six months after opening the account ,she made her first deposit of$ $ 1200 and continued depositing $1200 at the end of each six months period. interest was paid 3% per annum, compounded half yearly . How much was in Zina's account two years after first opening it

please help

Hey! This question is from the 2013 HSC Paper, and it is based on a formula on the old reference sheet that you no longer receive. This sort of question is no longer assessable, you don't need to know how to do it! ;D
Title: Re: General Math Q+A Thread
Post by: Potatohater on July 27, 2017, 11:35:07 am
What is interpolation and extrapolation?
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 27, 2017, 11:41:16 am
What is interpolation and extrapolation?
When you have a set of data, you may plot it on a graph and then sketch a line of best fit through it. An interpolation is when you use the line of best fit, to draw conclusion of something within the range of data.

E.g. Suppose you plotted weights (masses) on the x-axis, and heights on the y-axis. Suppose your weights range from 50kg to 80kg. You can then use your line of best fit to estimate what would be their height.

An extrapolation is functionally identical to an interpolation, but differs in that the actual value you're using is now outside the range of your data. In the above example, suppose your data still ranged from 50kg-80kg, but you wanted to approximate the height of a person who weighs 95kg. You would then have to extend your line of best fit far enough (this is the extrapolation) so that it allows you to perform this approximation.

(In practice, interpolation is generally quite safe if you know what you're doing, but there can be great risks involved when performing an extrapolation. Extending a line of best fit is not always optimal.)
Title: Re: General Math Q+A Thread
Post by: emilybrooks99 on July 27, 2017, 08:53:53 pm
Could someone walk me through how to get the answers to the following questions.

1) (http://uploads.tapatalk-cdn.com/20170727/841662dd461e77da78d3e74356468191.jpg)

2) (http://uploads.tapatalk-cdn.com/20170727/7735dcefbb93fbfbe1db1f53853ace84.jpg)

3) (http://uploads.tapatalk-cdn.com/20170727/f043bfd7caba2540e27089b58d85f224.jpg)

4) (http://uploads.tapatalk-cdn.com/20170727/2c8e91570e76115e39ec93c067a922df.jpg)

5) (http://uploads.tapatalk-cdn.com/20170727/34a0353a259d6b2ae5df2aa48338a02b.jpg)

Thank you!!
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 27, 2017, 09:07:59 pm
Could someone walk me through how to get the answers to the following questions.

1) (http://uploads.tapatalk-cdn.com/20170727/841662dd461e77da78d3e74356468191.jpg)

2) (http://uploads.tapatalk-cdn.com/20170727/7735dcefbb93fbfbe1db1f53853ace84.jpg)

3) (http://uploads.tapatalk-cdn.com/20170727/f043bfd7caba2540e27089b58d85f224.jpg)

4) (http://uploads.tapatalk-cdn.com/20170727/2c8e91570e76115e39ec93c067a922df.jpg)

5) (http://uploads.tapatalk-cdn.com/20170727/34a0353a259d6b2ae5df2aa48338a02b.jpg)

Thank you!!
It is very off-putting when a ton of questions are thrown at once. In the future, please consider posting lesser amounts, and asking the rest once those have been answered.


_________________________

_________________________

Title: Re: General Math Q+A Thread
Post by: Aaron12038488 on July 27, 2017, 09:09:46 pm
3. i think this is right, i dont do general math.
so we use the formula A= P(1+r)^n
so we know p is 5000
to find r, we do 8/100 / 12 = 0.06666....
to find n, 12x3 = 36
plug it in the formula u will get D
Note: I'm not sure if this is right, so yh.
Title: Re: General Math Q+A Thread
Post by: Shadowxo on July 27, 2017, 09:23:29 pm
Could someone walk me through how to get the answers to the following questions.

1) (http://uploads.tapatalk-cdn.com/20170727/841662dd461e77da78d3e74356468191.jpg)

2) (http://uploads.tapatalk-cdn.com/20170727/7735dcefbb93fbfbe1db1f53853ace84.jpg)

3) (http://uploads.tapatalk-cdn.com/20170727/f043bfd7caba2540e27089b58d85f224.jpg)

4) (http://uploads.tapatalk-cdn.com/20170727/2c8e91570e76115e39ec93c067a922df.jpg)

5) (http://uploads.tapatalk-cdn.com/20170727/34a0353a259d6b2ae5df2aa48338a02b.jpg)

Thank you!!

1. The interest per month is 8/12 = 0.666667%
Future value = initial amount * (1+growth rate)n
= 5000*(1+0.00666667)36 =D   (n = 36 months)

5. Is just rearranging

Note we don't have the ± as length can't be negative
Title: Re: General Math Q+A Thread
Post by: EEEEEEP on July 27, 2017, 09:30:31 pm
Could someone walk me through how to get the answers to the following questions.

1) (http://uploads.tapatalk-cdn.com/20170727/841662dd461e77da78d3e74356468191.jpg)

3) (http://uploads.tapatalk-cdn.com/20170727/f043bfd7caba2540e27089b58d85f224.jpg)
Thank you!!
(http://i.imgur.com/KcBy8Za.png)
Title: Re: General Math Q+A Thread
Post by: Shadowxo on July 27, 2017, 09:36:56 pm
3. Alternatively (good solution E6P though) we could use the graph
The graph is saying if you deposit $1 per period at an interest rate of r% per period, what the present value is
We know the interest rate is 4% per year so that means 2% per half year (interest compounded bi-annually)
There are 6 periods (6 half years in 3 years)
So $1 deposited per half-year at 2% per period is worth $5.601. Multiply it by 9000 (the amount deposited per half-year) and you get the same answer D :)
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 27, 2017, 09:43:06 pm
(http://i.imgur.com/KcBy8Za.png)
3. Alternatively (good solution E6P though) we could use the graph
The graph is saying if you deposit $1 per period at an interest rate of r% per period, what the present value is
We know the interest rate is 4% per year so that means 2% per half year (interest compounded bi-annually)
There are 6 periods (6 half years in 3 years)
So $1 deposited per half-year at 2% per period is worth $5.601. Multiply it by 9000 (the amount deposited per half-year) and you get the same answer D :)
They don't use annuity formulae nor have annuity methods. They must read a table that's been given to them.
________________

To read the table, the annuity factor is dependent on r and n.
n is the number of periods, and is equal to 6 as we deposit twice every year, for three yaers.
r is the rate per half-annum. 4% per annum becomes 2% per half year.

The annuity factor gives the present value of just $1. So if we want the present value of $9000 we have to multiply 9000 to that value on the table.

(That being said, I am very much annoyed at how they use "compounded biannually" to represent what's actually "semi-annual compounding". I have no idea where the logic works here.)
Title: Re: General Math Q+A Thread
Post by: EEEEEEP on July 27, 2017, 09:52:57 pm
(That being said, I am very much annoyed at how they use "compounded biannually" to represent what's actually "semi-annual compounding". I have no idea where the logic works here.)
It's an outdated term, but biannually has its roots in latin. Bi = two, So...... biannually = two times  a year =)
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 27, 2017, 09:54:43 pm
It's an outdated term, but biannually has its roots in latin. Bi = two, So...... biannually = two times  a year =)
The way I interpret compounded biannually is that I see bi as a prefix before the word "annual". So when I see this, I don't think compounded twice per year, but rather once per two years.

But if it is outdated, I sincerely hope it stays outdated.
Title: General Math Q+A Thread
Post by: stephanieazzopardi on July 28, 2017, 11:07:39 pm
Compounded biannually means compounding twice per year.
Title: Re: General Math Q+A Thread
Post by: emilybrooks99 on July 29, 2017, 09:00:29 am
Thank you so much!!!
Title: Re: General Math Q+A Thread
Post by: katie,rinos on July 30, 2017, 02:46:45 pm
Hey guys,
Could you please help with sections 2 and 3 of this question?
Also, might seem like a dumb question but what mode does the calculator need to be on to do the least-squares line of best fit? How do I get on that mode (I'm using the blue sharp calculator)?
Thanks so much!! :)
Title: Re: General Math Q+A Thread
Post by: Shadowxo on July 30, 2017, 03:05:57 pm
Hey guys,
Could you please help with sections 2 and 3 of this question?
Also, might seem like a dumb question but what mode does the calculator need to be on to do the least-squares line of best fit? How do I get on that mode (I'm using the blue sharp calculator)?
Thanks so much!! :)
So we know sin(ABC)=8/10 = 4/5 from i)
I'm assuming you're supposed to know the sin rule here

iii) You probably have to use a calculator here, using results from i) and ii) to find the angle

Good luck, let me know if you're still struggling with iii) :)
Title: Re: General Math Q+A Thread
Post by: katie,rinos on July 30, 2017, 03:29:48 pm
So we know sin(ABC)=8/10 = 4/5 from i)
I'm assuming you're supposed to know the sin rule here

iii) You probably have to use a calculator here, using results from i) and ii) to find the angle

Good luck, let me know if you're still struggling with iii) :)
Thanks so much, that definitely helped with part 3. I'm just a little bit confused, how did you get from the first to the second line of working out for the question (the 6 sin (ABP)/5)
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 30, 2017, 03:45:42 pm
Thanks so much, that definitely helped with part 3. I'm just a little bit confused, how did you get from the first to the second line of working out for the question (the 6 sin (ABP)/5)
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on August 01, 2017, 10:20:45 pm
Hey guys

I need help with working out the question... like how do I find the equation of the line?
Used the formula of y=mx+b but still didnt make sense...

Thanks in advance
Title: Re: General Math Q+A Thread
Post by: RuiAce on August 01, 2017, 10:27:34 pm

Hey guys

I need help with working out the question... like how do I find the equation of the line?
Used the formula of y=mx+b but still didnt make sense...

Thanks in advance
If you tried using that form, check that you found m=-1 and wrote down from the graph that b=2. You need to recall what m and b actually mean in that equation
Title: Re: General Math Q+A Thread
Post by: EEEEEEP on August 01, 2017, 10:38:28 pm
- y= mx + b
y = equation of a line
m = gradient
b = y intercept
...........
The Y intercept  (AKA b) is 2 (where the coordinate is 0,2).. b
Gradient = (y2 - y1)/(X2-X1)

Let point 1 = 0, 2
Let point  2 = 2, 0

m = (0--2)/(2-0) = -1

THerefore, the line... y = 2 - x
...
P.S. You can check your answer and see if it fits properly on the cartesian plane
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on August 02, 2017, 10:08:15 am
- y= mx + b
y = equation of a line
m = gradient
b = y intercept
...........
The Y intercept  (AKA b) is 2 (where the coordinate is 0,2).. b
Gradient = (y2 - y1)/(X2-X1)

Let point 1 = 0, 2
Let point  2 = 2, 0

m = (0--2)/(2-0) = -1

THerefore, the line... y = 2 - x
...
P.S. You can check your answer and see if it fits properly on the cartesian plane




THANK YOU SO SO MUCH REALLY MEANS A LOT TO ME! And now i know where I went wrong Thank you again
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on August 02, 2017, 10:36:41 am
Hey I'm back with another question

So this one really tripped me up because when I want to find 10% of something I usually times it by 0.1 and get the GST right?
So why is the answer D?

Thanks in advance
Title: Re: General Math Q+A Thread
Post by: RuiAce on August 02, 2017, 10:41:21 am
Hey I'm back with another question

So this one really tripped me up because when I want to find 10% of something I usually times it by 0.1 and get the GST right?
So why is the answer D?

Thanks in advance

Note that if the item cost represents 100% of the price it's to be sold at
and that the GST is 10% of this

Then the cost of the item WITH the GST combined is 110%.


Title: Re: General Math Q+A Thread
Post by: morning_sunshine on August 02, 2017, 10:44:27 am

Note that if the item cost represents 100% of the price it's to be sold at
and that the GST is 10% of this

Then the cost of the item WITH the GST combined is 110%.





Thank you so so! Can't believe that didn't cross my mind! Thank you :)
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on August 02, 2017, 11:27:06 am
Man I'm on a roll today

But I have an exam tomorrow so want to ask as many questions I need help with as possble.
I don't understand how to make a the subject after i bought r2 across to the other side

Like does the root a a2 cancel out the r2 and I only root the V?

Thanks in advance
Title: Re: General Math Q+A Thread
Post by: RuiAce on August 02, 2017, 12:15:00 pm
Man I'm on a roll today

But I have an exam tomorrow so want to ask as many questions I need help with as possble.
I don't understand how to make a the subject after i bought r2 across to the other side

Like does the root a a2 cancel out the r2 and I only root the V?

Thanks in advance
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on August 02, 2017, 01:14:49 pm


why did you then break the square root and put it on the two numbers ?
Title: Re: General Math Q+A Thread
Post by: EEEEEEP on August 02, 2017, 01:20:50 pm
why did you then break the square root and put it on the two numbers ?
(http://i.imgur.com/ljMVmlI.png)

A square root of a fraction is the same as the square root of the things inside the fraction (Top and bottom)
Title: Re: General Math Q+A Thread
Post by: RuiAce on August 02, 2017, 01:31:49 pm
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on August 02, 2017, 05:10:51 pm
Hey

So me being me I obviously assume the answer is 30%
So why is the answer 28%

Thanks in advance
Title: Re: General Math Q+A Thread
Post by: RuiAce on August 02, 2017, 05:16:18 pm
Hey

So me being me I obviously assume the answer is 30%
So why is the answer 28%

Thanks in advance



Title: Re: General Math Q+A Thread
Post by: jakesilove on August 02, 2017, 05:17:50 pm
Hey

So me being me I obviously assume the answer is 30%
So why is the answer 28%

Thanks in advance

Hey! Fair enough, this question was out to trick you from the start.

So, we have some total cost, let's call is $X. When we first get our 20% discount, we can find the total cost by multiplying $X by 80% (ie. Cutting out 20%).



Now, we want an EXTRA 10% discount. So, we have to discount the already discounted rate by another 10%: to do this, we multiple the total value by 90%



So, we have taken off 28% (1-0.72)

Title: Re: General Math Q+A Thread
Post by: morning_sunshine on August 02, 2017, 05:55:14 pm
Ok
Moving on I found this question
And before I came to the forum I wanted to see if I could do it myself and after sitting here for half an hour I have had no luck

Please help

Telling me the answer is 8 but I dont know how
Title: Re: General Math Q+A Thread
Post by: stephanieazzopardi on August 02, 2017, 06:24:24 pm
Ok
Moving on I found this question
And before I came to the forum I wanted to see if I could do it myself and after sitting here for half an hour I have had no luck

Please help

Telling me the answer is 8 but I dont know how

Hi there!

Ok so in order to see how many plants were actually sold in the week, we would require a cumulative frequency column, which will thus allow us to work out how on earth they got that mean.

So:
Cumulative frequency column (Number of plants purchased column x Frequency column)
8
38
3x
44
20
Total = 110 + 3x

The total of the frequency column in 42 + x

In this question, the person calculated the mean by dividing the sum of cumulative frequency column BY the sum of the frequency column
So, we would just solve for x using algebra, since we know what the mean already is.

(110 + 3x) / (42 + x) = 2.68

--> (110 + 3x) / 2.68 = (42 + x)
Times both sides by 2.68 to get rid of the fraction =
--> 110 + 3x = 2.68(42 +x)
Expand the brackets
--> 110 + 3x = 112.56 + 2.68x
Minus 110 from both sides
--> 3x = 2.56 + 2.68x
Minus -2.68x from both sides
--> 0.32x = 2.56
Solve for x
--> 0.32x / 0.32 = 2.56 / 0.32
     = 8

I hope that made sense!! :)

Title: General Math Q+A Thread
Post by: emilybrooks99 on August 09, 2017, 01:48:53 pm
Hey Could someone please help me with these questions and let me know which formulas to use. Thanks!
Title: Re: General Math Q+A Thread
Post by: RuiAce on August 09, 2017, 01:55:53 pm
Hey Could someone please help me with these questions and let me know which formulas to use. Thanks!


Title: Re: General Math Q+A Thread
Post by: EEEEEEP on August 09, 2017, 02:31:17 pm
Hey Could someone please help me with these questions and let me know which formulas to use. Thanks!
First Q
- Inflation is the rise in cost of certain products or services in a year.
1. Annualise the amount
2. Use the inflation rate to calculate the amount in 3 years (annual amount)
3. Divide it by 12
..
edit nvm. :P
Title: Re: General Math Q+A Thread
Post by: RuiAce on August 09, 2017, 04:08:22 pm
Isn't the first one just multiplication by 1.0263?
Title: Re: General Math Q+A Thread
Post by: bridie_2345 on August 12, 2017, 11:10:30 am
Hi there, I'm unsure of question 5. The answer is D through 1/13 X1/13 but I don't understand why it can't be 13/52 X 13/52

Thanks!
Title: Re: General Math Q+A Thread
Post by: RuiAce on August 12, 2017, 11:22:07 am
Hi there, I'm unsure of question 5. The answer is D through 1/13 X1/13 but I don't understand why it can't be 13/52 X 13/52

Thanks!
13 is the number of cards in a suit in the deck of cards. So if you wanted to draw, say, two spades, then it would be 13/52 * 13/52.

You want a specific rank (aka. value) for the card. There's only 4 of those; one in each suit, so we have 4/52 * 4/52.
Title: Re: General Math Q+A Thread
Post by: Juliesokha on August 13, 2017, 12:32:39 pm
Hello everyone,

I have my trails tomorrow (I know my school is weird but yea) and I need HELP - anyways I have given up on this probability question so bad rn, so can anyone please help me with it?

In a group of 32 people at a party, 20 are male and of those 2 are vegetarians. A third of the females at the party are vegetarians. A person is chosen at random from those at the party. What is the probability that they ARE NOT A VEGETARIAN?
a). 3/16
b). 3/8
c). 13/16
d). 15/16

Thank you <3
Title: Re: General Math Q+A Thread
Post by: RuiAce on August 13, 2017, 12:47:48 pm
Hello everyone,

I have my trails tomorrow (I know my school is weird but yea) and I need HELP - anyways I have given up on this probability question so bad rn, so can anyone please help me with it?

In a group of 32 people at a party, 20 are male and of those 2 are vegetarians. A third of the females at the party are vegetarians. A person is chosen at random from those at the party. What is the probability that they ARE NOT A VEGETARIAN?
a). 3/16
b). 3/8
c). 13/16
d). 15/16

Thank you <3



Title: Re: General Math Q+A Thread
Post by: Juliesokha on August 15, 2017, 11:47:32 am
Hello,

Also, this one as well.

Lauren owns 400 $3 ordinary shares and 300 $2 preferences shares. The current prices of the ordinary shares and preferences shares are $4.20 and $3.60 respectively. The dividend on the ordinary shares is 55c and on the preference shares is 3%. Calculate total dividend.
Title: Re: General Math Q+A Thread
Post by: EEEEEEP on August 15, 2017, 12:05:37 pm
Hello,

Also, this one as well.

Lauren owns 400 $3 ordinary shares and 300 $2 preferences shares. The current prices of the ordinary shares and preferences shares are $4.20 and $3.60 respectively. The dividend on the ordinary shares is 55c and on the preference shares is 3%. Calculate total dividend.
Let's gather some info.
1. 400 ord shares,
2. 300  Pref shares

Lets calculate dividends.
1. 400 x 0.55 = 220
2. 300 x (0.03 x $3.60) = 32.4

Total = 252.4
Title: Re: General Math Q+A Thread
Post by: Juliesokha on August 15, 2017, 08:42:32 pm
My goodness this looks sooooo easy but didn't we have to use the formula Dividend = Dividend Yield x Market Value?
Title: Re: General Math Q+A Thread
Post by: EEEEEEP on August 15, 2017, 08:47:32 pm
My goodness this looks sooooo easy but didn't we have to use the formula Dividend = Dividend Yield x Market Value?
Yes.

WHich is what I did  here (apologies for skipping a step :P)
" 300 x (0.03 x $3.60) = 32.4"
I multiplied the bracket by 300 as we had 300 preference shares =)
300 = no. pref shares
0.03 = the yield/percentage
3.6 = market price
Title: Can someone help with a question please
Post by: Aaron2230 on August 25, 2017, 02:02:19 pm
it is a question from my schools past exam papers, the question is on bearings but there is no solution for me to look at as it is a multi choice question.
Title: Re: Can someone help with a question please
Post by: RuiAce on August 25, 2017, 02:06:50 pm
it is a question from my schools past exam papers, the question is on bearings but there is no solution for me to look at as it is a multi choice question.



Title: Re: Can someone help with a question please
Post by: Aaron2230 on August 25, 2017, 02:11:00 pm
thanks
Title: Help with a question again plz
Post by: Aaron2230 on August 25, 2017, 02:48:36 pm
need help with a question, its somewhat simple just wanted to know ways to do it easy.
The question is the image below.
Title: Re: General Math Q+A Thread
Post by: RuiAce on August 25, 2017, 02:59:03 pm
need help with a question, its somewhat simple just wanted to know ways to do it easy.
The question is the image below.


Can't get easier than that
Title: Re: General Math Q+A Thread
Post by: Shadowxo on August 25, 2017, 03:32:28 pm
need help with a question, its somewhat simple just wanted to know ways to do it easy.
The question is the image below.
Or, alternatively, since they're similar the ratio of the sides is the same
CB/15 = 24/16
Or, CB/24 = 15/16
(Yes Rui it can get easier. Also, I think you meant cos instead of sin)
Title: Re: General Math Q+A Thread
Post by: Aaron2230 on August 25, 2017, 05:06:02 pm
Can u help me with this aswell, i thought it was (B) but its (A) how?

Martine buys stationary which costs $104.50 including GST. Because she works
for a charity she can claim the 10 % GST back from the taxation office. How
much GST can she claim?

(A) $9.50 (B) $10.45
(C) $95.00 (D) $94.05
Title: Re: General Math Q+A Thread
Post by: RuiAce on August 25, 2017, 05:26:41 pm
Or, alternatively, since they're similar the ratio of the sides is the same
CB/15 = 24/16
Or, CB/24 = 15/16
(Yes Rui it can get easier. Also, I think you meant cos instead of sin)
Similar triangles isn't really easier... they're the same. Saying by inspection we have similar ratios isn't endorsed in any HSC maths course without at minimal, reference to similarity.

But yeah, thanks for picking up on the typo
Can u help me with this aswell, i thought it was (B) but its (A) how?

Martine buys stationary which costs $104.50 including GST. Because she works
for a charity she can claim the 10 % GST back from the taxation office. How
much GST can she claim?

(A) $9.50 (B) $10.45
(C) $95.00 (D) $94.05

Title: Re: General Math Q+A Thread
Post by: Aaron2230 on August 27, 2017, 12:11:36 pm
Help with a question:

A car's petrol consumption (C) in litres/lOOkm can be estimated by using the formula: c=o.01s2 - s+33
where S is the speed (in km/h) at which the car is being driven.

What is the change in petrol consumption if the speed at which a car is being driven increases
from 60km/h to 80km/h?

(A) A decrease of 8 L/100km
(B) An increase of 8 L/100km
(C) A decrease of 17 L/100km
(D) An increase of 13.2 L/100km
Title: Re: General Math Q+A Thread
Post by: Natasha.97 on August 27, 2017, 12:21:14 pm
Help with a question:

A car's petrol consumption (C) in litres/lOOkm can be estimated by using the formula: c=o.01s2 - s+33
where S is the speed (in km/h) at which the car is being driven.

What is the change in petrol consumption if the speed at which a car is being driven increases
from 60km/h to 80km/h?

(A) A decrease of 8 L/100km
(B) An increase of 8 L/100km
(C) A decrease of 17 L/100km
(D) An increase of 13.2 L/100km


Hi!

Hope this helps
Title: Re: General Math Q+A Thread
Post by: Aaron2230 on August 27, 2017, 12:39:21 pm
Hi!

Hope this helps

yeah it did thanks just wanted to make sure i was doing it right  :)
Title: Re: General Math Q+A Thread
Post by: Adammurad on August 27, 2017, 04:59:57 pm
A fair coin is tossed 16 times.
a. Find the mean and standard deviation of the number of heads
appearing.
b. Show that the probability of the number of heads lying within two
standard deviations of the mean is approximately 0.95.
Anyone have a solution?
Title: Re: General Math Q+A Thread
Post by: RuiAce on August 27, 2017, 05:22:41 pm
A fair coin is tossed 16 times.
a. Find the mean and standard deviation of the number of heads
appearing.
b. Show that the probability of the number of heads lying within two
standard deviations of the mean is approximately 0.95.
Anyone have a solution?
I am not sure where this is from as this is not taught in the HSC general courses.
Title: Re: General Math Q+A Thread
Post by: emilybrooks99 on August 28, 2017, 05:17:47 pm
could someone please walk me through how to do simultaneous equations with the elimination method. thank you!
Title: Re: General Math Q+A Thread
Post by: EEEEEEP on August 28, 2017, 05:52:33 pm
could someone please walk me through how to do simultaneous equations with the elimination method. thank you!
The elimination method of solving systems of equations is also called the addition method. To solve a system of equations by elimination we transform the system such that one variable "cancels out" after adding...

Let say.... we have two equations..
x + y = 5              eq 1
2x -y = 10...        eq 2

1. Add eq 1 and 2
3x= 15......x =5

Sub x = 5.. into any of the above and we get y = 0.
Edit sorry...I did the wrong method....
Title: Re: General Math Q+A Thread
Post by: Natasha.97 on August 28, 2017, 06:33:15 pm
Hi!

This is a simultaneous equation involving 3 variables

(http://i.imgur.com/fezqgqB.png)

Hope this helps

Edit: Formatting
Title: Re: General Math Q+A Thread
Post by: Lachlan Morley on September 14, 2017, 05:47:07 pm
Hi guys,

Quick question about the Least Square line of best fit

When i find the gradient for the formula, sometime i would round off to diffrent decimal places then the answers for th standard deviations and amount of decimal places for the gradien

This , as a result, make my final equation slightly out to what the anwers have

If my equation is slightly out but i have shown full working, would i still get full marks and if not how can i ensure i round to the same decismals as the answers will

Thanks
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on September 14, 2017, 06:18:58 pm
Hi guys,

Quick question about the Least Square line of best fit

When i find the gradient for the formula, sometime i would round off to diffrent decimal places then the answers for th standard deviations and amount of decimal places for the gradien

This , as a result, make my final equation slightly out to what the anwers have

If my equation is slightly out but i have shown full working, would i still get full marks and if not how can i ensure i round to the same decismals as the answers will

Thanks


You would almost certainly get full marks as long as it is very close, if you are rounding you should try to take a few extra places than you'll actually need at the end! This will keep things more precise (not rounding at all, where possible, is always the best way) ;D
Title: Re: General Math Q+A Thread
Post by: Lachlan Morley on September 16, 2017, 10:17:51 am
You would almost certainly get full marks as long as it is very close, if you are rounding you should try to take a few extra places than you'll actually need at the end! This will keep things more precise (not rounding at all, where possible, is always the best way) ;D

ok great thanks jamon, for you online HSC holiday video lectures would you be able to do a sction on least sqaure line of best fit ?
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on September 16, 2017, 01:08:48 pm
ok great thanks jamon, for you online HSC holiday video lectures would you be able to do a sction on least sqaure line of best fit ?

I'm not doing the General Math videos, but I'll pass on the suggestion to Steph! ;D
Title: Re: General Math Q+A Thread
Post by: ca052267 on September 21, 2017, 11:08:32 am
Hi,

Is anyone able to help me with this question? (attached)

Thank you :)
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on September 21, 2017, 11:31:40 am
Hi,

Is anyone able to help me with this question? (attached)

Thank you :)


Sure! So we've found that \(\frac{20}{110}\) of penguins were tagged on the recapture. That means that, when we initially tagged our penguins, we tagged about \(\frac{20}{110}=\frac{2}{11}\) of the penguins. We initially caught 50 penguins, so our population \(P\) is:



Now we know that this is 13% less than 2012. Meaning, this population is 87% of 2012's population (we'll call this \(X\))!



So, the estimated population in 2012 must have been about 316! You can work it backwards too - Take 13% less than 316 and you get 275, and if you capture 50 out of 275 that is a fraction of 2 out of 11 ;D
Title: Re: General Math Q+A Thread
Post by: ca052267 on September 21, 2017, 11:54:41 am
Sure! So we've found that \(\frac{20}{110}\) of penguins were tagged on the recapture. That means that, when we initially tagged our penguins, we tagged about \(\frac{20}{110}=\frac{2}{11}\) of the penguins. We initially caught 50 penguins, so our population \(P\) is:



Now we know that this is 13% less than 2012. Meaning, this population is 87% of 2012's population (we'll call this \(X\))!



So, the estimated population in 2012 must have been about 259! You can work it backwards too - Take 13% less than 259 and you get 225, and if you capture 50 out of 225 that is a fraction of 2 out of 11 ;D


Thanks soo much.

But I think you may have a carried error, shouldn't the 2013 population come to 275 penguins?

Other than that, everything else makes sense.
Title: Re: General Math Q+A Thread
Post by: Shadowxo on September 21, 2017, 11:59:34 am

Thanks soo much.

But I think you may have a carried error, shouldn't the 2013 population come to 275 penguins?

Other than that, everything else makes sense.
Yep :) everything else (reasoning and formulas) are right though
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on September 21, 2017, 12:00:07 pm

Thanks soo much.

But I think you may have a carried error, shouldn't the 2013 population come to 275 penguins?

Other than that, everything else makes sense.

Ahh yep you're totally right, sorry about that!! Fixed up the answer - Glad I could help ;D
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on September 28, 2017, 02:16:55 pm
So I need help with this question

It's probably easier than what I'm thinking but some guidance would be great

So

What is the product of [8mn/9] and [15/6m] ?
Title: Re: General Math Q+A Thread
Post by: Eric11267 on September 28, 2017, 02:32:28 pm
So I need help with this question

It's probably easier than what I'm thinking but some guidance would be great

So

What is the product of [8mn/9] and [15/6m] ?

Or you could potentially do
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on September 28, 2017, 02:40:27 pm
Thanks so much! :)

Two more questions i came across

5.83ML is equivalent to ____________ kL

I wrote 5830kL
Is that wrong?

And then

What is the greatest possible error in the measurement 6.3L?

Thanks in advance :)
Title: Re: General Math Q+A Thread
Post by: Eric11267 on September 28, 2017, 02:42:47 pm
Thanks so much! :)

One more question i came across and i just want to make sure i got it right

5.83ML is equivalent to ____________ kL

I wrote 5830kL
Is that wrong?
If that's a conversion from megalitres to kilolitres then it is correct
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on September 28, 2017, 03:19:50 pm
Thanks again so so much :)

Another question because why not

The earth has a mass of 5.9723 x 10 to the power of 24kg. Express this correct to 2 significant figures.

How would I go about it?
Title: Re: General Math Q+A Thread
Post by: Eric11267 on September 28, 2017, 03:31:59 pm
Thanks again so so much :)

Another question because why not

The earth has a mass of 5.9723 x 10 to the power of 24kg. Express this correct to 2 significant figures.

How would I go about it?
Since theres only one number before the decimal point, rounding to two significant figures in this case is the same as rounding to one decimal place. Rounding 5.9723 to one decimal place gives you 6.0.

Another way of looking at it is if its asking for two significant figures you look at the third significant figure (in this case 7) and see if it is above or below 5. Then you would change the second significant figure accordingly. So since 7 is greater than five you, the 9 changes to a 0, which changes the 5 to a 6.

Hope this helps
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on September 28, 2017, 03:37:45 pm
Since theres only one number before the decimal point, rounding to two significant figures in this case is the same as rounding to one decimal place. Rounding 5.9723 to one decimal place gives you 6.0.

Another way of looking at it is if its asking for two significant figures you look at the third significant figure (in this case 7) and see if it is above or below 5. Then you would change the second significant figure accordingly. So since 7 is greater than five you, the 9 changes to a 0, which changes the 5 to a 6.

Hope this helps

So then would the answer be written as 6.0 x 10 to the power of 24
Or would it just be written as 6.0?
Title: Re: General Math Q+A Thread
Post by: RuiAce on September 28, 2017, 03:39:49 pm
So then would the answer be written as 6.0 x 10 to the power of 24
Or would it just be written as 6.0?
You will most certainly need the power of 24
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on September 28, 2017, 03:48:21 pm
Thanks so much :)
Much appreciate the help everyone :)

next up...

Erica owns 360 shares in a mining company. She paid $2.80 each for the shares and they are valued at $5.40 now. Erica received a dividend of $342
What was the dividend yield on the current market value of the shares?

How would I work out the current market value?
Title: Re: General Math Q+A Thread
Post by: RuiAce on September 28, 2017, 04:02:04 pm
Thanks so much :)
Much appreciate the help everyone :)

next up...

Erica owns 360 shares in a mining company. She paid $2.80 each for the shares and they are valued at $5.40 now. Erica received a dividend of $342
What was the dividend yield on the current market value of the shares?

How would I work out the current market value?

Note that we could also have done \( \frac{342/360}{5.40} \). The only thing that matters is that we consider the dividend for every 1 share, with the market value per 1 share. (In a way, the first method just considers the total number of shares that we have, whereas the second method does it on a unitary basis.)
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on September 28, 2017, 05:47:37 pm
Thank you Rui :) :) :)

Next question for ya....

Strong Credit Union has a credit card that requires a password of 6 digits and one of the letters A, B, C or D at the end. No digit may be used more than once.
How many different arrangements are possible?
Title: Re: General Math Q+A Thread
Post by: RuiAce on September 28, 2017, 07:10:54 pm
Thank you Rui :) :) :)

Next question for ya....

Strong Credit Union has a credit card that requires a password of 6 digits and one of the letters A, B, C or D at the end. No digit may be used more than once.
How many different arrangements are possible?

Title: Re: General Math Q+A Thread
Post by: ca052267 on October 05, 2017, 02:55:51 pm
Hi.
Can someone please help me with this question? It's from 2016 HSC, and I'm really confused.

27 (b) A small population consists of three students of heights 153 cm, 168 cm and 174 cm. Samples of varying sizes can be taken from this population.
What is the mean of the mean heights of all the possible samples? Justify your answer.



Thank you
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 06, 2017, 12:28:19 am
Hi.
Can someone please help me with this question? It's from 2016 HSC, and I'm really confused.

27 (b) A small population consists of three students of heights 153 cm, 168 cm and 174 cm. Samples of varying sizes can be taken from this population.
What is the mean of the mean heights of all the possible samples? Justify your answer.



Thank you

Hey! So we can add the three heights in the population up and divide by three to get the population mean:



Now the questions asks for the mean of every possible sample mean. Now look, you could just list every possible sample (there are only seven of them), find the sample mean of each (we just did one), then find the average of those values. However, we don't have to - The mean of all possible sample means IS the population mean! So you calculate the population mean as above, give that statement in bold, and you are done for two marks - You've found the answer ;D

Make sure you remember this little trick! It's actually a syllabus dot point by itself so super important :)
Title: Re: General Math Q+A Thread
Post by: ca052267 on October 06, 2017, 09:51:59 am
Thanks so much.

We didn't go through this in class, so I was really confused, but thanks for clearing it up for me :)
Title: Re: General Math Q+A Thread
Post by: dannoabdelnour on October 07, 2017, 07:59:20 pm
Hi!
I need to ask a question from a particular trial paper:

How many files of average size 1.5 MB can be stored on a 16 GB USB drive?
(A) 11
(B) 24
(C) 10 923
(D) 24 576

What i did was convert 16 GB to MB (16384MB) then i divided 16384 by 1.5 MB and got 10 922.66667, so I put C. I checked the answers to see if I got it right but the answers said it was D. They multiplied 16384 by 1.5 to get 24 576.

I tried to find a similar question to it and I did. This was from the 2014 HSC Specimen Paper:

Emma has 16 GB of data storage space available on her computer.
Approximately how many files of average size 7.2 MB can she store?
(A) 450
(B) 461
(C) 2222
(D) 2275

I did the exact same, I divided 16384MB by 7.2MB and got the right answer which was D.

Am I wrong or is this trial question wrong?

Thanks
Title: Re: General Math Q+A Thread
Post by: Natasha.97 on October 07, 2017, 08:18:33 pm
Hi!
I need to ask a question from a particular trial paper:

How many files of average size 1.5 MB can be stored on a 16 GB USB drive?
(A) 11
(B) 24
(C) 10 923
(D) 24 576

What i did was convert 16 GB to MB (16384MB) then i divided 16384 by 1.5 MB and got 10 922.66667, so I put C. I checked the answers to see if I got it right but the answers said it was D. They multiplied 16384 by 1.5 to get 24 576.

I tried to find a similar question to it and I did. This was from the 2014 HSC Specimen Paper:

Emma has 16 GB of data storage space available on her computer.
Approximately how many files of average size 7.2 MB can she store?
(A) 450
(B) 461
(C) 2222
(D) 2275

I did the exact same, I divided 16384MB by 7.2MB and got the right answer which was D.

Am I wrong or is this trial question wrong?

Thanks

Hey! Seems like they got the answers wrong to me :)
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 07, 2017, 08:21:42 pm
Hi!
I need to ask a question from a particular trial paper:

How many files of average size 1.5 MB can be stored on a 16 GB USB drive?
(A) 11
(B) 24
(C) 10 923
(D) 24 576

What i did was convert 16 GB to MB (16384MB) then i divided 16384 by 1.5 MB and got 10 922.66667, so I put C. I checked the answers to see if I got it right but the answers said it was D. They multiplied 16384 by 1.5 to get 24 576.

I tried to find a similar question to it and I did. This was from the 2014 HSC Specimen Paper:

Emma has 16 GB of data storage space available on her computer.
Approximately how many files of average size 7.2 MB can she store?
(A) 450
(B) 461
(C) 2222
(D) 2275

I did the exact same, I divided 16384MB by 7.2MB and got the right answer which was D.

Am I wrong or is this trial question wrong?

Thanks
Yeah, agree with Jess. That is one critically bad question
Title: Re: General Math Q+A Thread
Post by: Juliesokha on October 08, 2017, 06:01:09 pm
Where can I have access to some trail papers?! :) Thank you
Title: Re: General Math Q+A Thread
Post by: Natasha.97 on October 08, 2017, 06:02:41 pm
Where can I have access to some trail papers?! :) Thank you

THSC :)
Title: Re: General Math Q+A Thread
Post by: Juliesokha on October 08, 2017, 06:06:40 pm
THSC :)
You're too quick! <3 Thank youu
Title: Re: General Math Q+A Thread
Post by: sarahhamilton on October 09, 2017, 08:11:49 pm
What is the method of study for maths when I've done heaps of past papers?
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 09, 2017, 08:28:10 pm
What is the method of study for maths when I've done heaps of past papers?

How did you go in those Trial papers? Did you go back and re-attempt any questions you got wrong? That would the first thing I'd recommend ;D
Title: Re: General Math Q+A Thread
Post by: Savas_P on October 10, 2017, 06:50:41 pm
What is the method of study for maths when I've done heaps of past papers?

if you have done heaps, I assume you are getting them right, sounds like your ready for the exam!
Title: Re: General Math Q+A Thread
Post by: Juliesokha on October 11, 2017, 12:41:37 am
What is the method of study for maths when I've done heaps of past papers?

Heyy, samee but guess what? there is never enough to learn! So what I do is that I'll go back and do ALL of those papers again. I do them until the point that I sometimes even remember the answers to some of the questions!! (this sounds crazy but yea) ;D
Title: Re: General Math Q+A Thread
Post by: Potatohater on October 11, 2017, 08:00:58 am
Heyy, samee but guess what? it is never enough to learn! So what I do is that I'll go back and do ALL of those papers again. I do them until the point that I sometimes even remember the answers to some of the questions!! (this sounds crazy but yea) ;D
I've been doing this too! It got to a point where in my final internal assesment I recognised all the questions as past paper questions except a few, and it was my best exam because of it.
Title: Re: General Math Q+A Thread
Post by: bridie_2345 on October 12, 2017, 03:52:28 pm
Hi there the correct answer is B, could someone please explain how to do this? Thanks! X
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 12, 2017, 03:54:32 pm
Hi there the correct answer is B, could someone please explain how to do this? Thanks! X
This type of question has been removed from the syllabus as of 2014. (Back in the past, they were provided the formula for the PV of an annuity. It has now been removed.)
Title: Re: General Math Q+A Thread
Post by: bridie_2345 on October 19, 2017, 01:45:11 pm
hey there i was wondering if anyone had any questions that focus on the year 11 content needed for the general maths hsc exam? Thanks so much!
Title: Re: General Math Q+A Thread
Post by: ca052267 on October 20, 2017, 10:34:40 am
Questions like this always stuff me up.

Do I calculate the probability from the total surveyed, or the total number of males surveyed?
Title: Re: General Math Q+A Thread
Post by: katie,rinos on October 20, 2017, 10:48:48 am
Questions like this always stuff me up.

Do I calculate the probability from the total surveyed, or the total number of males surveyed?
Hey,
It's from the total surveyed as the question asks that the person is selected 'from the surveyed group' (which was the total 150 people)
Hope this helps :)
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 20, 2017, 10:52:30 am
Questions like this always stuff me up.

Do I calculate the probability from the total surveyed, or the total number of males surveyed?
On top of what Katie said, it's really about looking out for the wording.

When the question is given without some kind of "condition", you should anticipate that you're calculating a probability against the entire sample space. (Which is, of course, the surveyed group here.)

If instead, the question read something like "Out of all the males, how many do not own a mobile phone?" then you would have the condition that you're only considering the males. That's when you would divide by 70 and not 150.
Title: Re: General Math Q+A Thread
Post by: ca052267 on October 20, 2017, 11:23:36 am
Hey,
It's from the total surveyed as the question asks that the person is selected 'from the surveyed group' (which was the total 150 people)
Hope this helps :)
On top of what Katie said, it's really about looking out for the wording.

When the question is given without some kind of "condition", you should anticipate that you're calculating a probability against the entire sample space. (Which is, of course, the surveyed group here.)

If instead, the question read something like "Out of all the males, how many do not own a mobile phone?" then you would have the condition that you're only considering the males. That's when you would divide by 70 and not 150.


Thank you!!

I was stressing out because I usually get them right, but when I was marking, I got it wrong.

I realised afterwards that I had looked at the wrong answer... but at least you cleared it up. :)
Title: Re: General Math Q+A Thread
Post by: Aaron2230 on October 20, 2017, 11:29:49 am
Can someone explain to me how to find the upper and lower quartile again for this question i havent done it in a while. please and thank you
Title: Re: General Math Q+A Thread
Post by: ca052267 on October 20, 2017, 11:50:54 am
Can someone explain to me how to find the upper and lower quartile again for this question i havent done it in a while. please and thank you

Would the answer be 172-136 = 36?

From what I gathered you just calculate the quartile values straight form the ogive. Not sure if I'm right though..
Title: Re: General Math Q+A Thread
Post by: Aaron2230 on October 20, 2017, 12:22:10 pm
Would the answer be 172-136 = 36?

From what I gathered you just calculate the quartile values straight form the ogive. Not sure if I'm right though..
what i was wondering i how do i find the ogive again. the answer is correct just forgot how to do it
Title: Re: General Math Q+A Thread
Post by: Potatohater on October 20, 2017, 12:34:53 pm
Do we need to know the volume of a sphere?
Only the surface area formula is on the sheet and I don't remebr learning it but it's in the 2001 past paper I'm trying to do  :(
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 20, 2017, 12:37:06 pm
what i was wondering i how do i find the ogive again. the answer is correct just forgot how to do it
The graph is the ogive.

The ogive and the cumulative frequency polygon (aka cumulative frequency graph) are the same thing.
__________________________________________

Because in total we have 400 observations (or frequencies, not sure how you prefer to call it in general), the upper quartile is when the ogive reaches a cumulative frequency of 300. Additionally, the lower quartile is when the ogive reaches a cumulative frequency of 100.

From there, you just read across. It appears as though the cumulative frequency reaches 300 when the height reaches 172, and it reaches 100 when the height reaches 136. So 172 and 136 are the upper and lower quartiles (and as already mentioned, the difference between them is the IQR).
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 20, 2017, 12:42:06 pm
Do we need to know the volume of a sphere?
Only the surface area formula is on the sheet and I don't remebr learning it but it's in the 2001 past paper I'm trying to do  :(
The syllabus changed in 2013 and in the old formula sheet they give you the formula for the volume of a sphere.

Taking a look at the updated syllabus, I do not see it in the HSC Maths General 2 section (although I did see it in the General 1 section). So I presume it has been removed.

EDIT: I checked with Steph. It still appears from time to time so it's best to know the formula just in case.
Title: Re: General Math Q+A Thread
Post by: bridie_2345 on October 20, 2017, 01:54:34 pm
Hey there was just wanting to know the difference between frequency and relative frequency for probability?
Thanks heaps!
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 21, 2017, 10:25:51 am
Hey guys

So I have a few questions for whoever is lucky enough to answer these...
1. Make x the subject of the formula y=k-mx
      Now I get how to do it but in the worked solutions insted of y-k  it's telling me it is k-y/m    ?

2. Chloe holds a provisional license. Her allowable Blood Alcohol Content (BAC) to drive is zero. She knows that the liver breaks down alcohol at an average rate of 0.75 standard drinks per hour. If she consumed 10 standard drinks from 10pm to 2am what is the earliest time that she could legally drive to work?
A. 11.20 am
B. 11.33 am
C. 3.20 pm
D. 3.33 pm
    So since there is no mass I don't know what her BAC is. Am I supposed to work out her weight first and then continue or?

3. Ari borrowed $3340 for a period of 11 months. In total he repaid $4022. The simple interst rate per annum is:
A. (4022-3340) / (3340x11) x100%
B. (3340) / (4420x11) x100%
C. {12x(4022-3340)} / (3340x11) x100%
D. (12x3340) / (4022x11) x 100%

And finally
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 21, 2017, 10:31:41 am
Hey guys

So I have a few questions for whoever is lucky enough to answer these...
1. Make x the subject of the formula y=k-mx
      Now I get how to do it but in the worked solutions insted of y-k  it's telling me it is k-y/m    ?

2. Chloe holds a provisional license. Her allowable Blood Alcohol Content (BAC) to drive is zero. She knows that the liver breaks down alcohol at an average rate of 0.75 standard drinks per hour. If she consumed 10 standard drinks from 10pm to 2am what is the earliest time that she could legally drive to work?
A. 11.20 am
B. 11.33 am
C. 3.20 pm
D. 3.33 pm
    So since there is no mass I don't know what her BAC is. Am I supposed to work out her weight first and then continue or?

3. Ari borrowed $3340 for a period of 11 months. In total he repaid $4022. The simple interst rate per annum is:
A. 4022-3340/3340x11 x100%
B. 3340/4420x11 x100%
C. 12x(4022-3340)/3340x11 x100%
D. 12x3340/4022x11 x 100%

And finally

\begin{align*}y&=k-mx\\ y+mx&=k\\ mx&=k-y\\ x&=\frac{k-y}m\end{align*}
Is that screenshotted question really general math material? Like I know why the answer is B but it feels awkward trying to explain the reasoning for it because i don't know what general math students are taught.
Hey there was just wanting to know the difference between frequency and relative frequency for probability?
Thanks heaps!
Relative frequency is different in that it is the probability itself. Albeit, the experimental probability.

Suppose in 36 dice rolls the number five appeared 5 times. The frequency of five appearing was obviously just 5, but the relative frequency is 5/36.
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 21, 2017, 11:05:40 am
\begin{align*}y&=k-mx\\ y+mx&=k\\ mx&=k-y\\ x&=\frac{k-y}m\end{align*}
Is that screenshotted question really general math material? Like I know why the answer is B but it feels awkward trying to explain the reasoning for it because i don't know what general math students are taught.Relative frequency is different in that it is the probability itself. Albeit, the experimental probability.

Suppose in 36 dice rolls the number five appeared 5 times. The frequency of five appearing was obviously just 5, but the relative frequency is 5/36.


Thanks for your help! Yes the screenshotted one is a general maths trial question but I feel like I should know how to do it in case it comes up in the HSC ya know ;D
Title: Re: General Math Q+A Thread
Post by: yopenelope on October 21, 2017, 12:16:15 pm
I was wondering, if I'm ranked 20th in General for my school (ranked 20 out of 77) - Probably around 30 people that do general maths in my school gets pretty bad marks. & I know that general scales badly.. So i was wondering is it still possible for me to get a band 6 if I got 90-100% raw mark for my final HSC exam?
Title: Re: General Math Q+A Thread
Post by: Suffering on October 21, 2017, 02:30:41 pm
I don't know if this thing is still active but I've come across an issue, I've always learnt to NOT round in the middle of  a question in HSC general maths 2, however in doing past papers and going through the BOS answers for said papers I have noticed that they DO round in the middle of a question - so what am I supposed to do? I don't want to get all the answers wrong, but rounding in the middle of a question just seems wrong to me; even though BOS does it... Any help would be appreciated.
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 21, 2017, 02:38:46 pm
I was wondering, if I'm ranked 20th in General for my school (ranked 20 out of 77) - Probably around 30 people that do general maths in my school gets pretty bad marks. & I know that general scales badly.. So i was wondering is it still possible for me to get a band 6 if I got 90-100% raw mark for my final HSC exam?

Definitely possible! This guide has the specifics but that is definitely still achievable for you ;D

I don't know if this thing is still active but I've come across an issue, I've always learnt to NOT round in the middle of  a question in HSC general maths 2, however in doing past papers and going through the BOS answers for said papers I have noticed that they DO round in the middle of a question - so what am I supposed to do? I don't want to get all the answers wrong, but rounding in the middle of a question just seems wrong to me; even though BOS does it... Any help would be appreciated.

If you are concerned, don't round until the end! That is definitely considered correct even in the sample solutions do round earlier ;D
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 21, 2017, 02:40:27 pm

Thanks for your help! Yes the screenshotted one is a general maths trial question but I feel like I should know how to do it in case it comes up in the HSC ya know ;D
Well, I'm not sure how I can effectively convince a general student about it, but...
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 21, 2017, 02:57:51 pm
3. Ari borrowed $3340 for a period of 11 months. In total he repaid $4022. The simple interst rate per annum is:
A. 4022-3340/3340x11 x100%
B. 3340/4420x11 x100%
C. 12x(4022-3340)/3340x11 x100%
D. 12x3340/4022x11 x 100%
Can you please put some more brackets to emphasise what's going on with the fractions? A could easily be interpreted as \( 4022 - \frac{3340}{3340}\times 11 \times 100\text{percent} \)  even though you probably didn't mean it like that.
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 21, 2017, 04:14:06 pm
Ok thanks so much Rui means a lot

Could you help me with the other 2 that were mentioned also which I edited and placed below?

Thanks in advance :)

2. Chloe holds a provisional license. Her allowable Blood Alcohol Content (BAC) to drive is zero. She knows that the liver breaks down alcohol at an average rate of 0.75 standard drinks per hour. If she consumed 10 standard drinks from 10pm to 2am what is the earliest time that she could legally drive to work?
A. 11.20 am
B. 11.33 am
C. 3.20 pm
D. 3.33 pm
    So since there is no mass I don't know what her BAC is. Am I supposed to work out her weight first and then continue or?

3. Ari borrowed $3340 for a period of 11 months. In total he repaid $4022. The simple interst rate per annum is:
A. (4022-3340) / (3340x11) x100%
B. (3340) / (4420x11) x100%
C. {12x(4022-3340)} / (3340x11) x100%
D. (12x3340) / (4022x11) x 100%
Title: Re: General Math Q+A Thread
Post by: kaseyv on October 21, 2017, 04:42:41 pm
How to find the correlation coefficient r?? Are we meant to know a formula for that or will it not be in the HSC exam? I was doing a Sydney Grammar Trial paper and it asked to find the correlation coefficient...
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 21, 2017, 04:42:59 pm
3. Ari borrowed $3340 for a period of 11 months. In total he repaid $4022. The simple interst rate per annum is:
A. (4022-3340) / (3340x11) x100%
B. (3340) / (4420x11) x100%
C. {12x(4022-3340)} / (3340x11) x100%
D. (12x3340) / (4022x11) x 100%



So A.

(I'm leaving that other question for the time being because I'm not quite sure how to do it either, having not done general. Someone else might get to it before I get back to it.)
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 21, 2017, 04:44:27 pm
How to find the correlation coefficient r?? Are we meant to know a formula for that or will it not be in the HSC exam? I was doing a Sydney Grammar Trial paper and it asked to find the correlation coefficient...
According to the formula sheet, you can work backwards using the least squares line of best fit.

If it does not work, please post the actual question.
Title: Re: General Math Q+A Thread
Post by: studyharddd on October 21, 2017, 05:19:46 pm
Just wondering how to know when to use either the simple interest formula or compound interest formula and whats the difference? Unsure when to use which in some questions.
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 21, 2017, 05:25:20 pm
Just wondering how to know when to use either the simple interest formula or compound interest formula and whats the difference? Unsure when to use which in some questions.
I'm pretty sure they will state/hint when to use which. Please provide examples on where the confusion lies.
________________________

The main difference between simple interest and compound interest is generally overlooked. The difference lies in how the compounding actually happens.

In simple interest, we have a principal amount \( P \), and we only ever compound on top of it. This means that after one period, our interest calculated will be with respect to \( P\). After two periods, the amount will still be calculated with respect to \(P\).

In compound interest, we start with a principal amount \( P\), but we only ever compound on top of that one ONCE. Instead, after we compound it once, we then compound on the NEW amount. So whereas after one period we compound on top of \( P \), for the second period we compound on top of \( P \times \text{the interest factor} \) instead.

And well, the interest factor (a.k.a. compounding factor) is just a fancy name for \( 1+r \).
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 21, 2017, 05:39:50 pm



So A.

(I'm leaving that other question for the time being because I'm not quite sure how to do it either, having not done general. Someone else might get to it before I get back to it.)


Thank you so much Rui! Appreciate this so so much! You have no idea how grateful I am for your help!
The answers for this question say it's C ?
Which is why I was confused also

What do you think I should do?
Stick with the answer being A?
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 21, 2017, 05:43:38 pm
One more question I have for you :( 
Sorry for alll the questions
but here it is

Alice was driving her car at 40 km/h through a school zone.
A school student ran onto the road 15 metres in front of her.
If her reaction time is 0.50 seconds and her braking distance was 7.9 metres, was Alice able to stop her car without hitting the child?
Show calculations to support.

Title: Re: General Math Q+A Thread
Post by: RuiAce on October 21, 2017, 05:49:00 pm

Thank you so much Rui! Appreciate this so so much! You have no idea how grateful I am for your help!
The answers for this question say it's C ?
Which is why I was confused also

What do you think I should do?
Stick with the answer being A?
Oops, that's my fault.

I completely forgot that \(n\) was measured in years, not months. Because that's the case, \( n = \frac{11}{12}\), not just 11. That's my fault - fixing it now
Title: Re: General Math Q+A Thread
Post by: emilybrooks99 on October 21, 2017, 07:08:45 pm
can someone explain how to answer this please!
thanks
(http://uploads.tapatalk-cdn.com/20171021/1a2bf40e3ee33728936fea2fe7b7ff65.jpg)
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 21, 2017, 07:09:57 pm
I feel so bad for asking so many questions  :'(

But I am stuck on how they found the sixty in the angle of ABC

There's no form of alternate angles that would lead me to believe the 60 is formed from that so I really would love some clarification

Thanks in advance

Regards
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 21, 2017, 07:11:11 pm
can someone explain how to answer this please!
thanks
(http://uploads.tapatalk-cdn.com/20171021/1a2bf40e3ee33728936fea2fe7b7ff65.jpg)


Title: Re: General Math Q+A Thread
Post by: RuiAce on October 21, 2017, 07:19:56 pm
One more question I have for you :( 
Sorry for alll the questions
but here it is

Alice was driving her car at 40 km/h through a school zone.
A school student ran onto the road 15 metres in front of her.
If her reaction time is 0.50 seconds and her braking distance was 7.9 metres, was Alice able to stop her car without hitting the child?
Show calculations to support.




Or you could've just divided by 3.6 straight away for the conversion.

I hope I did this right but again I cannot guarantee that I did.

Therefore yes she was able to stop her car and save the lucky little soul
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 21, 2017, 07:26:33 pm
I feel so bad for asking so many questions  :'(

But I am stuck on how they found the sixty in the angle of ABC

There's no form of alternate angles that would lead me to believe the 60 is formed from that so I really would love some clarification

Thanks in advance

Regards
(https://i.imgur.com/Ci8g7e8.png)
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 21, 2017, 08:49:37 pm
(https://i.imgur.com/Ci8g7e8.png)

Following this question
they ask how far the ship is from its starting point?

I used the cosine rule and didnt get the correct answer ?

What else can i do?
Title: Re: General Math Q+A Thread
Post by: Potatohater on October 21, 2017, 10:01:49 pm
Following this question
they ask how far the ship is from its starting point?

I used the cosine rule and didnt get the correct answer ?

What else can i do?

Have you tried the sine rule?
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 21, 2017, 10:04:53 pm
Following this question
they ask how far the ship is from its starting point?

I used the cosine rule and didnt get the correct answer ?

What else can i do?

This should've given \(d=169.12\). What was their answer?
Title: Re: General Math Q+A Thread
Post by: pvee123 on October 21, 2017, 10:07:06 pm
Lel this is a stupid question, but is compound interest, annuity, and future value the same thing or?
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 21, 2017, 10:11:00 pm
Lel this is a stupid question, but is compound interest, annuity, and future value the same thing or?


So if we had a hypothetical scenario with 6% p.a. interest rate and 1000 principal, then after 5 years this would've been compounded up to \( 1000(1.06)^5\).

In the case of an annuity, you would be given 1000 every year, not just the first year. Its value will accumulate to \( 1000(1.06)^5 + 1000(1.05)^4 + \dots + 1000(1.05)^1 \), because you gained an extra $1000 at the start of EVERY year.
________________________________

The FV of the above cash flow in five years will be exactly \(1000(1.06)^5\). But its FV in three years would've only been \(1000(1.06)^3\). Its present value is just 1000

The computation of a FV is done through the means of compound interest. Compound interest is just the name for a method; future value is the name for the result of the method.
Title: Re: General Math Q+A Thread
Post by: pvee123 on October 21, 2017, 10:21:18 pm
Thank you so much, you're amazing!
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 09:47:35 am

This should've given \(d=169.12\). What was their answer?

That was the answer they gave but when I put it in my calculator it comes up with 28602.21092

Why is that?
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 22, 2017, 09:50:48 am
That was the answer they gave but when I put it in my calculator it comes up with 28602.21092

Why is that?

Did you remember to square root?
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 10:09:30 am
Did you remember to square root?

No I did not do that OMG I am so sillyyyy!

THANK YOU SO SO SO SO SO SO SO MUCH I HONESTLY DON'T KNOW WHAT I WOULD DO WITHOUT YOUR HELP!!!!!!  ;D ;D
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 11:37:59 am
Hey I have a question from last year's HSC paper

So I keep getting my answer either in the 80s range (so D) or in the 50s range which isn't an option.

The answers say C which if I round my answer up and give a guess is right but I want to know how to get C without having to base it on luck ya know

Thanks in advance
Title: Re: General Math Q+A Thread
Post by: EEEEEEP on October 22, 2017, 11:54:03 am
Hey I have a question from last year's HSC paper

So I keep getting my answer either in the 80s range (so D) or in the 50s range which isn't an option.

The answers say C which if I round my answer up and give a guess is right but I want to know how to get C without having to base it on luck ya know

Thanks in advance
P (smoker or male) = P (smoker ) + P (male) - P (smoker AND MALE)

which equals to....

264/465 + 156/465 - 88/465 = .6845
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 11:59:49 am
P (smoker or male) = P (smoker ) + P (male) - P (smoker AND MALE)

which equals to....

264/465 + 156/465 - 88/465 = .6845

THANK YOU SO MUCH!!!!!
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 12:02:40 pm
So practice makes perfect, and its questions like these that get me so worked up.

So i've tried so many different formulas, you name it I probably tried it and didnt get the right answer....
How do I find the bearing of C from B?

:( :'(
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 22, 2017, 12:34:34 pm

So practice makes perfect, and its questions like these that get me so worked up.

So i've tried so many different formulas, you name it I probably tried it and didnt get the right answer....
How do I find the bearing of C from B?

:( :'(


(https://i.imgur.com/Qk1cYO6.png)
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 12:52:31 pm


(https://i.imgur.com/Qk1cYO6.png)


Could you explain to me how you solved the formula please! I don't mean to be a pain  :'(

Thanks in advance
Title: Re: General Math Q+A Thread
Post by: Natasha.97 on October 22, 2017, 01:00:54 pm
Could you explain to me how you solved the formula please! I don't mean to be a pain  :'(

Thanks in advance

Hi!

Title: Re: General Math Q+A Thread
Post by: Juliesokha on October 22, 2017, 02:17:40 pm
Can someone please help me with this question? :)
Title: Re: General Math Q+A Thread
Post by: Natasha.97 on October 22, 2017, 02:32:00 pm
Can someone please help me with this question? :)

Hi!

When taking the cube root of 857.375, we get 9.5 as the answer. If it was less than 9.75, the cube length would get rounded down to 9.5, but if it was 9.76 or larger, it would be rounded up to 10. Therefore, the largest possible volume would be 9.753 which is 926.86 (A)

Hope this helps
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 02:38:07 pm
So another question

What do you do in this question ...
Like how do you go about it

Title: Re: General Math Q+A Thread
Post by: Natasha.97 on October 22, 2017, 02:41:15 pm
So another question

What do you do in this question ...
Like how do you go about it



Hi!

Jamon's already addressed this question here :)
Title: Re: General Math Q+A Thread
Post by: emilybrooks99 on October 22, 2017, 02:43:17 pm
If we use the nPr and nCr calculator functions for probability in the exam what working out do we show? And will we lose any marks?
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 02:45:24 pm
Hi!

Jamon's already addressed this question here :)

THANK YOU SO MUCH HUN!!
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 02:45:37 pm
If we use the nPr and nCr calculator functions for probability in the exam what working out do we show? And will we lose any marks?

Just checked with our General lecturer, you:

Write what you put into the calculator itself, then just write what it gives you. No working necessary, and you won't lose marks (if the answer is right of course!) ;D
Title: Re: General Math Q+A Thread
Post by: kneehaha on October 22, 2017, 03:11:51 pm
Hey!
I do the General Math course, and have been struggling with Simultaneous equations. No matter how many videos i watch, and questions i attempt, it just doesnt work out for me! I was wondering if there are any tips etc to get this down pat.
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 22, 2017, 03:13:52 pm
Hey!
I do the General Math course, and have been struggling with Simultaneous equations. No matter how many videos i watch, and questions i attempt, it just doesnt work out for me! I was wondering if there are any tips etc to get this down pat.
Please expand on your problem or provide examples (stating which method(s) you would like help on) for more advice. Some general advice for the time being:

1. You always have a choice of whether you want substitution or elimination.
2. Your method doesn't have to be the exact same as provided in sample solutions, so long as it still flows correctly and hence gets to the correct answer
3. Make sure you understand how the elimination and substitution method works.


Edit: Incorporated Jamon's comment since they're always linear
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 03:17:03 pm
Hey!
I do the General Math course, and have been struggling with Simultaneous equations. No matter how many videos i watch, and questions i attempt, it just doesnt work out for me! I was wondering if there are any tips etc to get this down pat.

Hey!! A few tips from our General lecturer:

- Use the method you are more comfortable with (though know both in case they specify a method)
- When in doubt, just get one of the equations to the point where it has \(y\) as the subject - You can then use the substitution method to substitute this equation into the other
- If using elimination method, get all your variables on one side and look for the same value in both equations, eg, a \(2x\) appearing in both. That is the clue for using the elimination method, and you just subtract the equations (if they are the same sign) or add the equations (if they are different sign, \(2x\) versus \(-2x\) for example) :)

Also remember that we solve these equations to find a point of intersection, so make sure you provide both the \(x\) and \(y\) coordinates clearly at the end ;D I think this is very much a practice makes perfect thing!

2. When they are all linear terms (e.g. \(2x+3y=4\) and \(6x-y=-12\) then you always have a choice of whether you want substitution or elimination.

All of your equations in the General Course will look like this, there are no non-linear terms like \(x^2\) or anything like that ;D
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 03:30:37 pm
2. Chloe holds a provisional license. Her allowable Blood Alcohol Content (BAC) to drive is zero. She knows that the liver breaks down alcohol at an average rate of 0.75 standard drinks per hour. If she consumed 10 standard drinks from 10pm to 2am what is the earliest time that she could legally drive to work?
A. 11.20 am
B. 11.33 am
C. 3.20 pm
D. 3.33 pm
    So since there is no mass I don't know what her BAC is. Am I supposed to work out her weight first and then continue or?

Hey! Sorry this took a while but I wanted to run it past Steph - This is actually a bit of a trick, because we aren't given the standard info we just use some intuition. We know she starts drinking at 10pm, and can break down 0.75 standard drinks per hour from that point. She needs to break down 10 drinks - This takes:



So if we count forward this much from 10pm, we get 11:20am - The answer should be A ;D
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 03:31:31 pm
Ok so not sure if this question has been addressed but if its asking for what amount can be picked out of the jar why id it 4/37 when there is 37 in his hand?

It just confuses me
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 03:35:31 pm
Ok so not sure if this question has been addressed but if its asking for what amount can be picked out of the jar why id it 4/37 when there is 37 in his hand?

It just confuses me

Hey! So when he grabs that handful, it is representative of the amount of coins total in the jar. So the probability of finding a gold coin in the jar is the same as finding it in his hand - It's random sampling ;D

So that is why it is \(\frac{4}{37}\), because the sample is representative of the population, so to speak ;D
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 03:37:58 pm
Hey! Sorry this took a while but I wanted to run it past Steph - This is actually a bit of a trick, because we aren't given the standard info we just use some intuition. We know she starts drinking at 10pm, and can break down 0.75 standard drinks per hour from that point. She needs to break down 10 drinks - This takes:



So if we count forward this much from 10pm, we get 11:20am - The answer should be A ;D

THANK YOUUU SO MUCH CLEARER NOW
It really did trick me
Title: Re: General Math Q+A Thread
Post by: Rainbowhippocampus on October 22, 2017, 04:03:48 pm
Hi there, just wondering how to calculate monthly repayments?  Is there a formula for it?
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 04:09:48 pm
Hi there, just wondering how to calculate monthly repayments?  Is there a formula for it?

I think I know the question type you mean, and you are always given an annuities table for an annuities type question. You use the table ;D

Did you have an example of something you are struggling with?
Title: Re: General Math Q+A Thread
Post by: Rainbowhippocampus on October 22, 2017, 04:18:47 pm
I think I know the question type you mean, and you are always given an annuities table for an annuities type question. You use the table ;D

Did you have an example of something you are struggling with?

2010 HSC
mark needs $8000 for a holiday in three years time.  He has a holiday savings account with a balance of $600. He arranges to deposit $150 into this account at the end of each month for the next 3 years.  He earns 6% per annum interest on the money in the account (book says to change this to 39.3361), compounded monthly.  Will mark have enough money for his trip at the end of three years?  Justify your answer with suitable calculations.   
These are the sorts of Qs catching me off guard
Title: Re: General Math Q+A Thread
Post by: harry77 on October 22, 2017, 04:22:11 pm
hello

i need help with this question pls, i am a little confused as to working this out

thanks  :) :D
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 22, 2017, 04:23:26 pm
hello

i need help with this question pls, i am a little confused as to working this out

thanks  :) :D

This one was answered quite recently
Title: Re: General Math Q+A Thread
Post by: harry77 on October 22, 2017, 04:25:04 pm
thanks sorry missed the solution before
Title: Re: General Math Q+A Thread
Post by: britt.jayne on October 22, 2017, 04:27:38 pm
Hi....  :D
This is probably a dumb question but i can't understand why the answer for the attached question is A? I got B and can't quite figure out why it is A...
Thanks heaps... very much appreciated!!!!!!!....
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 22, 2017, 04:29:47 pm
Hi....  :D
This is probably a dumb question but i can't understand why the answer for Q4 in the 2012 General Maths HSC Paper is A? I got B and can't quite figure out why it is B... here is the link to the paper... it is Q4 and is about the expression used to calculate the value of x in the particular triangle...
https://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2012exams/pdf_doc/2012-hsc-exam-general-maths.pdf
Thanks heaps... very much appreciated!!!!!!!....


But of course you don't want sin in there, because all of their answers have cos in them.
So you need to consider the other angle (the \(40^\circ\) instead)
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 04:33:16 pm
Hi....  :D
This is probably a dumb question but i can't understand why the answer for the attached question is A? I got B and can't quite figure out why it is A...
Thanks heaps... very much appreciated!!!!!!!....

Hey! So we know that the cosine ratio is ADJACENT over HYPOTENUSE, think SOHCAHTOA ;D

So, we do that cosine ratio for the angle of 40 degrees in the bottom corner:



Now multiply both sides by 29, the one on the right will cancel, leaving us:



That's where A comes from! Does it help? :)
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 04:35:39 pm
So how would I find the value of A in this instance?

Like I tried making A the subject but that wasn't so successful so what should I do?

Thanks in advance

Title: Re: General Math Q+A Thread
Post by: britt.jayne on October 22, 2017, 04:38:43 pm
THANKS SO MUCH!!!!! I ACTUALLY UNDERSTAND NOW!!!!  ;D ;D I was looking at it totally wrong!!!....
i'm really hoping i don't make any stupid mistakes tomorrow!!!!!  ???
thanks again!!!!!!
Title: Re: General Math Q+A Thread
Post by: MisterNeo on October 22, 2017, 04:40:47 pm
So how would I find the value of A in this instance?

Like I tried making A the subject but that wasn't so successful so what should I do?

Thanks in advance

From the graph, you can see that when x(days)=0, the Mass is 1.5. You would sub these into the equation and then solve for A. ;)
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 04:48:41 pm
From the graph, you can see that when x(days)=0, the Mass is 1.5. You would sub these into the equation and then solve for A. ;)


MAKES SO MUCH SENSE!
I kept reading m as 1 which is probs why i kept getting it wrong
THANK YOUU
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 04:53:07 pm
From the graph, you can see that when x(days)=0, the Mass is 1.5. You would sub these into the equation and then solve for A. ;)


but then how would I find the daily growth rate of the pig?
Like is there a formula or something coz the answers literally just give me the answer
Title: Re: General Math Q+A Thread
Post by: harry77 on October 22, 2017, 04:58:06 pm
hello
how do i figure the IQR out pls help
thanks
Title: Re: General Math Q+A Thread
Post by: pvee123 on October 22, 2017, 05:10:09 pm
Is Medicare Levy, tax deductible?
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 05:19:46 pm
hello
how do i figure the IQR out pls help
thanks

Hey! So the \(IQR\) is the middle 50%, or in this case, the middle 200 students. So, we look at the difference in height from the 100 student mark on the cumulative frequency axis, to the 300 student mark (the middle 200 students).

172cm - 136cm = 36cm ;D

This is just like going Q3 - Q1, but we get the values from a graph ;D this is a hard question! Does it make sense? :)
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 05:20:22 pm
Is Medicare Levy, tax deductible?

Nope, it is an amount you pay on top of your regular tax contribution ;D
Title: Re: General Math Q+A Thread
Post by: harry77 on October 22, 2017, 05:25:08 pm
thanks so much jamon :D it finally makes sense now!!
Title: Re: General Math Q+A Thread
Post by: harry77 on October 22, 2017, 05:28:03 pm
i am having trouble with this can you help pls!!

this question is from last yrs paper,

thanks
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 05:30:22 pm
i am having trouble with this can you help pls!!

this question is from last yrs paper,

thanks

Hey! I don't have the values from higher up to do it numerically, but the idea will be:

VOLUME OF RECTANGULAR PRISM - VOLUME OF 24 SMALL CYLINDERS

You need the volume of the big rectangular prism (used the depth and radius of the marshmallows), and then subtract 24 lots of the volume of the marshmallow. The difference is your chocolate (if this question doesn't make you hungry nothing will) ;D
Title: Re: General Math Q+A Thread
Post by: harry77 on October 22, 2017, 05:35:21 pm
here is the question from above for the marshmallow one
sorry pls explain further?
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 05:40:28 pm
here is the question from above for the marshmallow one
sorry pls explain further?

Sure! So the dimensions of that big prism of marshmallows can be found by clever adding of the dimensions, it is 20cm by 15cm by 6cm, see if you can spot how they line up. The volume is:



But that's counting the gaps as well - The volume of the marshmallows is just the 24 times the volume of the cylinder. Remember the radius is half the diameter:



Multiply by 24 to get the total marshmallow volume:



And the difference between the two is your answer - The gaps where the chocolate will go...

Edit: Almost. Except the chocolate only goes into half the gaps I am speaking about. So to get the final answer, we halve that final answer ;D

Title: Re: General Math Q+A Thread
Post by: harry77 on October 22, 2017, 05:42:22 pm
but then how would I find the daily growth rate of the pig?
Like is there a formula or something coz the answers literally just give me the answer

hello
i need help with this too? pls
thanks
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 05:46:21 pm
but then how would I find the daily growth rate of the pig?
Like is there a formula or something coz the answers literally just give me the answer


Could you upload the question specifically? ;D

and maybe their answer too? Sorry just want to make sure I interpret it correctly :)
Title: Re: General Math Q+A Thread
Post by: harry77 on October 22, 2017, 05:54:53 pm
here u r
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 06:01:40 pm
here u r

Cool! So you can tell from the formula they use, the 1.1 is the giveaway, but you can also tell by picking any two days and comparing. Say Day 1 and Day 2:



Then we just divide Day 2 by Day 1 and we get:



So the Day 2 mass is 110% of the Day 1 mass, a growth of 10%! You could do this with any two days and it would work - Or you could spot it in the formula they use ;D
Title: Re: General Math Q+A Thread
Post by: MisterNeo on October 22, 2017, 06:05:53 pm
hello
i need help with this too? pls
thanks


Title: Re: General Math Q+A Thread
Post by: Rainbowhippocampus on October 22, 2017, 06:28:34 pm
Hey there, question do we have to remember the different dosage formulas for children and adults?
Thank you
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 06:30:31 pm
Hey there, question do we have to remember the different dosage formulas for children and adults?
Thank you

Nope, they will be given to you! ;D
Title: Re: General Math Q+A Thread
Post by: Rainbowhippocampus on October 22, 2017, 06:36:37 pm
AWESOME THANK YOU
Title: Re: General Math Q+A Thread
Post by: [MA165] on October 22, 2017, 06:44:46 pm
Hey! ;D
i find probability really confusing in this course... especially trying to work out what technique as such to apply and when...
so... is nPr applied to unordered data as such... eg) something that can be used more than once.... and nCr used when things can only be used once... eg) selecting people for a committee?
sorry... that possibly made no sense??! :o

Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 06:52:36 pm
Hey! ;D
i find probability really confusing in this course... especially trying to work out what technique as such to apply and when...
so... is nPr applied to unordered data as such... eg) something that can be used more than once.... and nCr used when things can only be used once... eg) selecting people for a committee?
sorry... that possibly made no sense??! :o

Welcome to the forums! I instead like to think of it as:

- nPr is when order does mattter
- nCr is when order doesn't matter

For example, if there are 10 people and I'm selecting 5 for a committee, then that can happen in 10C5 ways. But if I'm, say, voting for 5 of them in order of preference (order matters), it would be 10P5 ways.

In general, you can always choose the things only once, but it's whether you care about the order when you are done or not that determines which you use ;D
Title: Re: General Math Q+A Thread
Post by: [MA165] on October 22, 2017, 06:58:32 pm
Welcome to the forums! I instead like to think of it as:

- nPr is when order does mattter
- nCr is when order doesn't matter

For example, if there are 10 people and I'm selecting 5 for a committee, then that can happen in 10C5 ways. But if I'm, say, voting for 5 of them in order of preference (order matters), it would be 10P5 ways.

In general, you can always choose the things only once, but it's whether you care about the order when you are done or not that determines which you use ;D


Ohh!! ;D i get it!! Thankyou v much!!!!

Title: Re: General Math Q+A Thread
Post by: emilybrooks99 on October 22, 2017, 07:14:01 pm
Can someone help me out with this question and explain it thoroughly cause standard deviation is where I always go wrong. Thanks
(http://uploads.tapatalk-cdn.com/20171022/a9169f2ff537fb5bb625786c1a24e7e0.jpg)
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 07:24:40 pm
Can someone help me out with this question and explain it thoroughly cause standard deviation is where I always go wrong. Thanks
(http://uploads.tapatalk-cdn.com/20171022/a9169f2ff537fb5bb625786c1a24e7e0.jpg)

Hey! So with a mean of 3.1kg, we need to look at everything with respect to the standard deviation of 0.35kg. Notice that 2.75kg is one standard deviation below the mean and 4.15kg is three standard deviations above the mean.

This diagram does the best job showing how much is in each of those standard deviations:

(https://i.imgur.com/BycJNhC.png)

We want from -1 to 3, from one standard deviation below to three above. Add those percentages up:



And then find how many babies this is:

Title: Re: General Math Q+A Thread
Post by: [MA165] on October 22, 2017, 08:20:43 pm
Hey... is anyone able to help me out on how to go about this question? ???
it refers to the question before which just states what is found in a deck of 52 cards... 4 suits,  each suit has 9 numbers, one ace, and a jack, queen and king...
MANY THANKS!
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 08:30:33 pm
Hey... is anyone able to help me out on how to go about this question? ???
it refers to the question before which just states what is found in a deck of 52 cards... 4 suits,  each suit has 9 numbers, one ace, and a jack, queen and king...
MANY THANKS!

Hey! So you should try drawing a tree diagram of the three draws, with each draw either yielding a number card or a non-number card. Remember the probabilities will change on the second and third draws because this is without replacement!

Then you just use the tree diagram like normal to solve. Multiply along the relevant branches. So, for example, the probability of zero number cards is just the product of the probabilities along that single branch:



You'll need to add the probabilities of a few branches to calculate the probability of holding two number cards, but hopefully this gives you the idea! Let us know how you travel ;D
Title: Re: General Math Q+A Thread
Post by: Shadowxo on October 22, 2017, 08:53:56 pm
Sure! So the dimensions of that big prism of marshmallows can be found by clever adding of the dimensions, it is 20cm by 15cm by 6cm, see if you can spot how they line up. The volume is:



But that's counting the gaps as well - The volume of the marshmallows is just the 24 times the volume of the cylinder. Remember the radius is half the diameter:



Multiply by 24 to get the total marshmallow volume:



And the difference between the two is your answer - The gaps where the chocolate will go ;D
Wouldn't that include the 'gaps' outside the marshmallow cake (but within the rectangle) where the chocolate doesn't go?

Area of one of the chocolate bits = area of one of the 5x5 squares - area of one circle (as there are four quarter-circles per 'square')
= 5*5 - π*2.52 = 5.365 cm2
Volume of one of the chocolate bits = area*height = 5.365*6 = 32.19 cm3
Volume of all 6 chocolate bits = 6*32.19=193.1 cm3

Alternatively, you could just halve the answer Jamon got, as that would be the volume of 12 of the chocolate bits instead of 6 :)
Title: Re: General Math Q+A Thread
Post by: themangopomegranate on October 22, 2017, 09:22:24 pm
Hello there, can someone please help me with these questions? I never quite understood random samples and how to use them to solve questions😅 - like how do i generate random numbers on my calculator? *question b onwards 😊 (http://)
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 09:26:06 pm
Wouldn't that include the 'gaps' outside the marshmallow cake (but within the rectangle) where the chocolate doesn't go?

Area of one of the chocolate bits = area of one of the 5x5 squares - area of one circle (as there are four quarter-circles per 'square')
= 5*5 - π*2.52 = 5.365 cm2
Volume of one of the chocolate bits = area*height = 5.365*6 = 32.19 cm3
Volume of all 6 chocolate bits = 6*32.19=193.1 cm3

Alternatively, you could just halve the answer Jamon got, as that would be the volume of 12 of the chocolate bits instead of 6 :)

Ahh too clever, thanks for the correction Shadow! ;D
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 09:33:16 pm
Hello there, can someone please help me with these questions? I never quite understood random samples and how to use them to solve questions😅 - like how do i generate random numbers on my calculator? *question b onwards 😊 ()

A random sample is just a way to guess stuff about your population using a small, randomly selected subset. EG, guessing the average height of all 20 year old males by looking at the height of a few 20 year old males.

Take a random sample of \(n=5\) to be the top 5 people in that table. Persons 1-5. It could be any five people!

Of those 5, 2/5=40% drive a car, 2/5=40% catch a bus, and 1/5=20% walk. This is data from our sample, and if we compare it to the total percentage for the population:

20% walk
40% drive
40% bus

It is actually identical - So in this case, our sample does a fantastic job as an estimate, we got lucky! But different samples will be slightly less effective, purely based on chance ;D
Title: Re: General Math Q+A Thread
Post by: themangopomegranate on October 22, 2017, 09:38:16 pm
A random sample is just a way to guess stuff about your population using a small, randomly selected subset. EG, guessing the average height of all 20 year old males by looking at the height of a few 20 year old males.

Take a random sample of \(n=5\) to be the top 5 people in that table. Persons 1-5. It could be any five people!

Of those 5, 2/5=40% drive a car, 2/5=40% catch a bus, and 1/5=20% walk. This is data from our sample, and if we compare it to the total percentage for the population:

20% walk
40% drive
40% bus

It is actually identical - So in this case, our sample does a fantastic job as an estimate, we got lucky! But different samples will be slightly less effective, purely based on chance ;D

Ahhh that's makes so much more sense, thank you so much ! For some reason I always thought it was something more complex 😅
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 09:39:50 pm
Ahhh that's makes so much more sense, thank you so much ! For some reason I always thought it was something more complex 😅


Hate when things get over-complicated! Glad I could help - Good luck in your exam tomorrow (if you are in Year 12, aha) ;D
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 09:41:53 pm
Hey
So this is probs easier than I think it is but I think my mind is turning off and just doesnt want to work anymore but I'm pushing through ahahah
 :o

Anyway, how would i find the distance for this

BTW soz for that TMI
Title: Re: General Math Q+A Thread
Post by: themangopomegranate on October 22, 2017, 09:44:52 pm
Hate when things get over-complicated! Glad I could help - Good luck in your exam tomorrow (if you are in Year 12, aha) ;D

😁😁 Yes I have the exam tomorrow and thank you, again !!
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 09:46:27 pm
Hey
So this is probs easier than I think it is but I think my mind is turning off and just doesnt want to work anymore but I'm pushing through ahahah
 :o

Anyway, how would i find the distance for this

BTW soz for that TMI


Hey! So the angle of depression is 42 degrees, but that appears ABOVE the line in the triangle. The way this works though is that the 42 degree angle of depression appears in the bottom angle of the triangle, at the buoy - Is this something you are familiar with happening?

If so, it is easy. Use the tan ratio (SOHCAHTOA!):



Multiply by \(d\):



Then divide by tan and calculate:



Does this help? :)
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 09:53:09 pm
Hey! So the angle of depression is 42 degrees, but that appears ABOVE the line in the triangle. The way this works though is that the 42 degree angle of depression appears in the bottom angle of the triangle, at the buoy - Is this something you are familiar with happening?

If so, it is easy. Use the tan ratio (SOHCAHTOA!):



Multiply by \(d\):



Then divide by tan and calculate:



Does this help? :)

Yes this helps so so much!

Honestly don't know how I didn't remember this

Gosh really hope my brain is on the ball tomorrow

THANK YOU SO SO MUCH! LIFESAVER :) :D
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 22, 2017, 09:53:57 pm
Yes this helps so so much!

Honestly don't know how I didn't remember this

Gosh really hope my brain is on the ball tomorrow

THANK YOU SO SO MUCH! LIFESAVER :) :D

Stay relaxed, underline key terms in the question - It will come to you as you need it! Good luck! ;D
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 09:57:27 pm
Stay relaxed, underline key terms in the question - It will come to you as you need it! Good luck! ;D

THANK YOU!
I'll be sure to check in with you after the exam :)

Best advice ever hoenstly!
THANKS SO MUCH HONESTLY DON'T KNOW WHERE I WOULD BE WITHOUT YOUR HELP :) :D
Title: Re: General Math Q+A Thread
Post by: emilybrooks99 on October 22, 2017, 09:59:23 pm
How do we calculate the correlation coefficient? I've tried to find it in my textbook but i've had no luck
Title: Re: General Math Q+A Thread
Post by: [MA165] on October 22, 2017, 10:10:34 pm
How do we calculate the correlation coefficient? I've tried to find it in my textbook but i've had no luck

Generally its calculated from a range of data with x and y variables.... which is where the calculator come handy... this is just how i have learnt to do it :D... so basically with the x and y data.. enter it into the calculator (on stats mode, select 2: (a+b X)- gives you a table)
and once you have entered in the data press AC then shift 1, then 5 (reg) then 3 (r)... somewhat of a process.... ??? but that should do it... :)
ATB
Title: Re: General Math Q+A Thread
Post by: morning_sunshine on October 22, 2017, 10:18:05 pm
Another question that's popped up

A camera costs $449, including 12% GST.
    What is the price of the camera without GST, correct to the nearest dollar?
(A)    $395
(B)    $401
(C)    $437
(D)    $503

PLEASE HELP :'(
Title: Re: General Math Q+A Thread
Post by: EEEEEEP on October 22, 2017, 10:23:16 pm
Another question that's popped up

A camera costs $449, including 12% GST.
    What is the price of the camera without GST, correct to the nearest dollar?
(A)    $395
(B)    $401
(C)    $437
(D)    $503

PLEASE HELP :'(
401 is the answer =)

Since there is 12% GST, then it is currently priced at 1.12X

X = price prior to GST...

So... 449/1.12 = 400.89, (round up for the nearest dollar)
Title: Re: General Math Q+A Thread
Post by: [MA165] on October 22, 2017, 10:25:38 pm
Another question that's popped up

A camera costs $449, including 12% GST.
    What is the price of the camera without GST, correct to the nearest dollar?
(A)    $395
(B)    $401
(C)    $437
(D)    $503

PLEASE HELP :'(


Hey!
I would answer this by dividing 449 by 112% which gives you 400.89.... rounded up to 401... i would say B?!
Title: Re: General Math Q+A Thread
Post by: bridbrid2000 on October 22, 2017, 10:49:19 pm
Hey i have a question from the 2016 HSC paper its question number 25 there is a diagram given but i cant figure out whether it has attached so there is a link to the paper bellow aswell.
thanks in advance

25) The diagram shows towns A, B and C. Town B is 40 km due north of town A. The
distance from B to C is 18 km and the bearing of C from A is 025°. It is known that BCA
is obtuse.
What is the bearing of C from B?
(A) 070°
(B) 095°
(C) 110°
(D) 135°

http://educationstandards.nsw.edu.au/wps/wcm/connect/06a68d63-e1aa-4616-b0fe-5144a7a8ed0d/2016-hsc-maths-general-2.pdf?MOD=AJPERES&CACHEID=ROOTWORKSPACE-06a68d63-e1aa-4616-b0fe-5144a7a8ed0d-lCpNxTo

Title: Re: General Math Q+A Thread
Post by: [MA165] on October 22, 2017, 11:00:01 pm
Hey i have a question from the 2016 HSC paper its question number 25 there is a diagram given but i cant figure out whether it has attached so there is a link to the paper bellow aswell.
thanks in advance

25) The diagram shows towns A, B and C. Town B is 40 km due north of town A. The
distance from B to C is 18 km and the bearing of C from A is 025°. It is known that BCA
is obtuse.
What is the bearing of C from B?
(A) 070°
(B) 095°
(C) 110°
(D) 135°

http://educationstandards.nsw.edu.au/wps/wcm/connect/06a68d63-e1aa-4616-b0fe-5144a7a8ed0d/2016-hsc-maths-general-2.pdf?MOD=AJPERES&CACHEID=ROOTWORKSPACE-06a68d63-e1aa-4616-b0fe-5144a7a8ed0d-lCpNxTo

Basically you use the sine rule to find out value of the angle opposite the 40km side
so sin X / 40 = sin 25 / 18.... this equal 70 (rounded) but because it identifies that this is an obtuse angle, you have to minus it from 180 (180-70 = 110)
now that you have 2 angles (one already given)... you do (180- 110- 25) = 45 and as you are trying to find the bearing of C from B.... and B to A is a straight line... just do supplementary angles 180-45.... equals 135... therefore D... :D
Title: Re: General Math Q+A Thread
Post by: emilybrooks99 on October 22, 2017, 11:03:06 pm

Generally its calculated from a range of data with x and y variables.... which is where the calculator come handy... this is just how i have learnt to do it :D... so basically with the x and y data.. enter it into the calculator (on stats mode, select 2: (a+b X)- gives you a table)
and once you have entered in the data press AC then shift 1, then 5 (reg) then 3 (r)... somewhat of a process.... ??? but that should do it... :)
ATB

thank you!!
Title: Re: General Math Q+A Thread
Post by: Juliesokha on October 22, 2017, 11:11:42 pm
Hey i have a question from the 2016 HSC paper its question number 25 there is a diagram given but i cant figure out whether it has attached so there is a link to the paper bellow aswell.
thanks in advance

25) The diagram shows towns A, B and C. Town B is 40 km due north of town A. The
distance from B to C is 18 km and the bearing of C from A is 025°. It is known that BCA
is obtuse.
What is the bearing of C from B?
(A) 070°
(B) 095°
(C) 110°
(D) 135°


hope this helps :)

Title: Re: General Math Q+A Thread
Post by: yopenelope on October 23, 2017, 01:24:11 pm
Hey I just did my General Math HSC exam and i was wondering if the question was 'Calculate the volume of the cone' and it had a sphere on top with the bottom of the sphere entering part of the cone, and in my answer i had the working out for the height to use in the formula for the cone, and the 'Volume of the cone with part of the sphere' and 'Volume of the cone without part of the sphere' beacuse I didn't know what they meant. Would they mark me down for going a step further for stating 'volume of the cone with part of the sphere' or just be able to neglect it and not get marked down?
Title: Re: General Math Q+A Thread
Post by: PrincePringle on October 23, 2017, 01:56:38 pm
Hey I just did my General Math HSC exam and i was wondering if the question was 'Calculate the volume of the cone' and it had a sphere on top with the bottom of the sphere entering part of the cone, and in my answer i had the working out for the height to use in the formula for the cone, and the 'Volume of the cone with part of the sphere' and 'Volume of the cone without part of the sphere' beacuse I didn't know what they meant. Would they mark me down for going a step further for stating 'volume of the cone with part of the sphere' or just be able to neglect it and not get marked down?

Unfortunately you may lose a mark or two, but it really depends on the marking criteria they develop. What was your final answer?
Title: Re: General Math Q+A Thread
Post by: yopenelope on October 23, 2017, 02:08:19 pm
Unfortunately you may lose a mark or two, but it really depends on the marking criteria they develop. What was your final answer?


I didnt get to finish but the 'v of the cone without part of sphere' working out was on the extra writing space - except I hadn't rounded off the 'v of the cone with part of sphere' (what they were looking for) because i was going to round off at the end

So if it was 3 marks, would I only get 1 mark?
Title: Re: General Math Q+A Thread
Post by: erhulloollie on October 23, 2017, 02:26:51 pm

I didnt get to finish but the 'v of the cone without part of sphere' working out was on the extra writing space - except I hadn't rounded off the 'v of the cone with part of sphere' (what they were looking for) because i was going to round off at the end

So if it was 3 marks, would I only get 1 mark?
Hey... i also just sat the general maths exam.... for the last question i just found the volume of the cone regardless of the sphere sitting in a bit... the sphere was just there to help find the dimensions of the cone.... so my final answer was 113 cubic cm...!
Did anyone else get anything similar..??
Title: Re: General Math Q+A Thread
Post by: erhulloollie on October 23, 2017, 02:31:19 pm
Hey yopenelope!
How did you find the rest of the paper... and how did you go for time..??
Title: Re: General Math Q+A Thread
Post by: erhulloollie on October 23, 2017, 02:45:14 pm
Hi Stephanie Azzopardi,
Just thought i'd let you know, I ordered your ATAR Notes HSC Mathematics General 2 Edition 1, and on page 8 the capacity conversions is wrong..!!
But despite that... a very helpful condensed set of notes... helped a lot!! Thank you!! :D
Title: Re: General Math Q+A Thread
Post by: PrincePringle on October 23, 2017, 02:46:03 pm
Hey... i also just sat the general maths exam.... for the last question i just found the volume of the cone regardless of the sphere sitting in a bit... the sphere was just there to help find the dimensions of the cone.... so my final answer was 113 cubic cm...!
Did anyone else get anything similar..??

Yeah. i got 113 cm^3.

I sense you used pythagoras and used the height of the cone as 9 as I did?
Title: Re: General Math Q+A Thread
Post by: erhulloollie on October 23, 2017, 02:48:30 pm
Yeah. i got 113 cm^3.

I sense you used pythagoras and used the height of the cone as 9 as I did?
yep that's it... i asked our maths teacher after the exam and he has seen the paper... and he said that sounded right... so hope for the best..!!
Title: Re: General Math Q+A Thread
Post by: Aayamstha7 on October 23, 2017, 03:03:28 pm
Hey, i did all the working out to find out 113cm (cubed) (volume of the sphere), unfortunately i overthought it and tried to minus the hemispshere in the cone. how many marks could i expect to lose?
Title: Re: General Math Q+A Thread
Post by: erhulloollie on October 23, 2017, 03:24:56 pm
Hey, i did all the working out to find out 113cm (cubed) (volume of the sphere), unfortunately i overthought it and tried to minus the hemispshere in the cone. how many marks could i expect to lose?
I'm not totally sure... it depends on the marking criteria!
It was a 3 mark question from memory so you would probably still get 2/3
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on October 23, 2017, 03:44:07 pm
We've got an exam discussion going for you guys, see here!
Title: Re: General Math Q+A Thread
Post by: PrincePringle on October 23, 2017, 08:56:59 pm
me too!! thanks
Title: General Math Q+A Thread
Post by: Lumenoria on November 30, 2017, 12:05:34 pm
Hi, I'm doing a question;
For a reducing balance loan of 180000 at 9% over 12 yrs, with fortnightly repayments of 932.75, find;
a. Total interest payable
b. The equivalent flat rate of interest annually
I was wondering if theres a method to calculate total interest payable (for a) without manually drawing out the whole table? In this case, you would have to draw 312 rows (12x26 fortnights) and I swear that's not the most efficient way, but the textbook doesnt mention anything otherwise.

And I'm just at a complete loss as to how you would do b
Title: Re: General Math Q+A Thread
Post by: huss1235 on November 30, 2017, 12:48:11 pm
Hi, I'm doing a question;
For a reducing balance loan of 180000 at 9% over 12 yrs, with fortnightly repayments of 932.75, find;
a. Total interest payable
b. The equivalent flat rate of interest annually
I was wondering if theres a method to calculate total interest payable (for a) without manually drawing out the whole table? In this case, you would have to draw 312 rows (12x26 fortnights) and I swear that's not the most efficient way, but the textbook doesnt mention anything otherwise.

And I'm just at a complete loss as to how you would do b

Hi okay this is how i would do the question    *= multiply  /=divide
a) 932.75*26=24251.5 that is per year as there is 26 fortnights now for 12 years you do 24251.5*12=291018
now 291018-180000=111018 which is the total interest payable
b) okay so for this question begin with the simple interest formula which is I=PRN
now to find I( intrest  ) you make it the subject of the formula which is r= I/P*N
now the interest is total repayable - the principle which is 291018-180000= 111018 therefore the answer will be
111018/ 180000(the principle)*12 years = answer* 100
which is 5.14% to 2dp
if you dont understand or need anything feel free to ask
thanks

Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on November 30, 2017, 12:55:21 pm
Hi, I'm doing a question;
For a reducing balance loan of 180000 at 9% over 12 yrs, with fortnightly repayments of 932.75, find;
a. Total interest payable
b. The equivalent flat rate of interest annually
I was wondering if theres a method to calculate total interest payable (for a) without manually drawing out the whole table? In this case, you would have to draw 312 rows (12x26 fortnights) and I swear that's not the most efficient way, but the textbook doesnt mention anything otherwise.

And I'm just at a complete loss as to how you would do b

Hey! Just clarifying on Huss' answer above:

- For (a), you need to subtract the principal from that final answer to get interest payable. So the answer to (a) is actually that number $111,018 :)
- And just clarifying for (b), it is \(R\) you are making the subject of the formula, which is:



Substituting those values as Huss has shown you will get you the answer :)
Title: Re: General Math Q+A Thread
Post by: huss1235 on November 30, 2017, 12:56:30 pm
Hey! Just clarifying on Huss' answer above:

- For (a), you need to subtract the principal from that final answer to get interest payable. So the answer to (a) is actually that number $111,018 :)
- And just clarifying for (b), it is \(R\) you are making the subject of the formula, which is:



Substituting those values as Huss has shown you will get you the answer :)
yeah i just noticed i forgot to subtract after i read the question again i edited it  and i said i was missing the R
Title: Re: General Math Q+A Thread
Post by: LegalEagle24/7 on January 25, 2018, 06:13:55 pm
Two simple suggestions:

Use a highlighter.
Copy out valuable pieces of information CLEARLY stating what it is on the SIDE.

Hi! Some people from my class told us that you can only use a pink highlighter in the HSC exams. Is this true? Thanks :)
Title: Re: General Math Q+A Thread
Post by: RuiAce on January 25, 2018, 06:18:47 pm
Hi! Some people from my class told us that you can only use a pink highlighter in the HSC exams. Is this true? Thanks :)
Never heard of that rule before. NESA doesn't specify anything regarding the colour either
Title: Re: General Math Q+A Thread
Post by: LegalEagle24/7 on January 25, 2018, 07:01:25 pm
Never heard of that rule before. NESA doesn't specify anything regarding the colour either

Cool, thanks. :) Because they said that they only allowed pink as it's the only colour they are able to see when scanning the papers.
Title: Re: General Math Q+A Thread
Post by: Potatohater on January 25, 2018, 07:55:17 pm
Cool, thanks. :) Because they said that they only allowed pink as it's the only colour they are able to see when scanning the papers.
When I did the HSC just a few months ago our supervisor told us not to mark the paper with any highlighters or any implement other than a black pen so....
Title: Re: General Math Q+A Thread
Post by: RuiAce on January 25, 2018, 08:05:14 pm
Cool, thanks. :) Because they said that they only allowed pink as it's the only colour they are able to see when scanning the papers.
If you're unsure it might be a good idea to send them an email. To be fair, they did change their scanning system quite recently (idk why though, it was for the WORSE if you ask me) so no guarantees that things that were ok are still ok. Plus you never know if they update their website.

Having said that though
When I did the HSC just a few months ago our supervisor told us not to mark the paper with any highlighters or any implement other than a black pen so....
That would literally contradict the website itself, which is really odd.
___________________

TLDR: Just email NESA
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on January 25, 2018, 09:19:23 pm
Note that you can highlight any colour you like on the questions, because they don't need to read those ;D
Title: Re: General Math Q+A Thread
Post by: Lumenoria on February 05, 2018, 08:04:50 pm
Hey, is there a way to calculate the interquartile range without writing/ordering every single number on paper? Like, say there were 200 numbers, is there a proper formula for this?
Title: Re: General Math Q+A Thread
Post by: emilyygeorgexx on February 05, 2018, 08:16:38 pm
Hey, is there a way to calculate the interquartile range without writing/ordering every single number on paper? Like, say there were 200 numbers, is there a proper formula for this?

Hey!

If you didn't want to calculate the IQR by hand, you can just pop the numbers on the calculator (if you have the scientific one) and it will calculate the IQR for you!
Title: Re: General Math Q+A Thread
Post by: Razeen25 on March 09, 2018, 01:14:06 am
Now that the website is back online...Yes. Keep in mind that maths is different to every other subject in that the preliminary course is EXAMINABLE. Up to 20% of the final exams are allowed to include content taught in the preliminary course.

Anything goes in maths. All of it is in play.

I NEVER KNEW THIS. I dropped to general at the start of year 12, and I guess now I’m just realising the immense workload I must catch up with - that is, all the prelim content I never learnt. Why math gotta do peeps who drop down like this smh  :'(
Title: Re: General Math Q+A Thread
Post by: Potatohater on March 09, 2018, 08:44:31 am
I NEVER KNEW THIS. I dropped to general at the start of year 12, and I guess now I’m just realising the immense workload I must catch up with - that is, all the prelim content I never learnt. Why math gotta do peeps who drop down like this smh  :'(
It'll be ok, I did the same, and since the HSC content is mostly an extension of the prelim content you won't have to work too hard to catch up if you've got a solid understanding of the HSC content, which, from mathematics 2U I guess you do. A lot of it's pretty easy, the only things I remember having to distinctly go over because I didn't already know them from yr10 and below, is the yr11 case studies and some of the financial stuff, but other than that going over the whole course isn't super nessecary
Title: Re: General Math Q+A Thread
Post by: joemassoud on March 09, 2018, 08:53:25 am
Hey Guys,

If anyone could please explain this question and what exactly is a linear function is and how to identify one

Thanks in advance!

Title: Re: General Math Q+A Thread
Post by: RuiAce on March 09, 2018, 08:56:10 am
Hey Guys,

If anyone could please explain this question and what exactly is a linear function is and how to identify one

Thanks in advance!


The linear function must take the form \(y=mx+b\), meaning only y’s and x’s appear. The only plausible option is B, which is \(y=-x+12\) rearranged.

A fails because of the \(\frac1x\), whih makes it a hyperbola
C fails because of the \(x^2\), which makes it a quadratic (parabola)
D fails because of the \(2^x\), which makes it an exponential
Title: Re: General Math Q+A Thread
Post by: joemassoud on March 30, 2018, 04:24:07 pm
Hey Guys,

I have my half yearly coming up next week and the topics being assessed are:

1. Loans and Annuities
2. Equations and Linear Functions
3. Further Applications of Area and Volume
4. Statistical Distributions

I have completed all my school's past papers and topic tests given by my teacher. If anyone can send me or let me know of any past paper resources or topic tests on the topics above that would be awesome!

Thanks!
Title: Re: General Math Q+A Thread
Post by: Potatohater on March 30, 2018, 09:14:45 pm
Hey Guys,

I have my half yearly coming up next week and the topics being assessed are:

1. Loans and Annuities
2. Equations and Linear Functions
3. Further Applications of Area and Volume
4. Statistical Distributions

I have completed all my school's past papers and topic tests given by my teacher. If anyone can send me or let me know of any past paper resources or topic tests on the topics above that would be awesome!

Thanks!

Have you tried the HSC papers yet? You coul either sift through them manually looking for those topics or find a book that groups them together such as the checkpoints book
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on March 30, 2018, 11:59:19 pm
Hey Guys,

I have my half yearly coming up next week and the topics being assessed are:

1. Loans and Annuities
2. Equations and Linear Functions
3. Further Applications of Area and Volume
4. Statistical Distributions

I have completed all my school's past papers and topic tests given by my teacher. If anyone can send me or let me know of any past paper resources or topic tests on the topics above that would be awesome!

Thanks!

Only because you asked for a suggestion, the ATAR Notes Topic Tests would be worth a look! I personally think they are incredible, and everything is divided by topic to make things easy to study :)
Title: Re: General Math Q+A Thread
Post by: emilyygeorgexx on March 31, 2018, 07:51:23 pm
I NEVER KNEW THIS. I dropped to general at the start of year 12, and I guess now I’m just realising the immense workload I must catch up with - that is, all the prelim content I never learnt. Why math gotta do peeps who drop down like this smh  :'(

Omg I feel you on another level! I dropped from 2U in the last term of Year 11, which meant I had to sit the General Maths Yearly. I had to learn everything they had covered in the whole year, and it was hard at first because of all the work I had missed and some of the concepts I had never seen before so I was like wtf. But it does get easier after that, you'll be so sweet and there's no reason to stress.

I legit had my half yearly on Monday this week and I have no idea how but I finished with 55 minutes to spare. Don't worry I didn't just sit there, I went back over my paper and redid some questions where I found mistakes. ;D

Fingers crossed I actually did well!!
Title: Re: General Math Q+A Thread
Post by: Lumenoria on April 01, 2018, 09:55:40 am
Hey, for this question, do I calculate the cumulative frequency based on the first 163 or the last one?
Title: Re: General Math Q+A Thread
Post by: RuiAce on April 01, 2018, 10:09:48 am
Hey, for this question, do I calculate the cumulative frequency based on the first 163 or the last one?
The last.

The cumulative frequency is intended to be a running total of all the frequencies, so every instance of 163 must count as well. Therefore 10 is correct.
Title: Re: General Math Q+A Thread
Post by: Razeen25 on April 01, 2018, 01:45:41 pm
Hey, for this question, do I calculate the cumulative frequency based on the first 163 or the last one?

I’m actually confused. How do you calculate the cumulative frequency from a stem and leaf plot?
Title: Re: General Math Q+A Thread
Post by: Lumenoria on April 01, 2018, 02:04:28 pm

The last.

The cumulative frequency is intended to be a running total of all the frequencies, so every instance of 163 must count as well. Therefore 10 is correct.
Thankyou!!
Title: Re: General Math Q+A Thread
Post by: Lumenoria on April 01, 2018, 02:07:10 pm
Okay, so this is the solution on the answers for a past trial paper I've been doing, but I swear to god it's wrong - or I'm just really stupid. Can someone please confirm? My answer is waaay off this, and I swear I haven't done anything wrong because I've gotten the same answer three times. I don't understand why they've minused the a and the b when the formula clearly states you're supposed to add them?
Title: Re: General Math Q+A Thread
Post by: emilyygeorgexx on April 01, 2018, 02:18:57 pm
Okay, so this is the solution on the answers for a past trial paper I've been doing, but I swear to god it's wrong - or I'm just really stupid. Can someone please confirm? My answer is waaay off this, and I swear I haven't done anything wrong because I've gotten the same answer three times. I don't understand why they've minused the a and the b when the formula clearly states you're supposed to add them?

Hey!

You need to plus the upper base and lower base of the trapezium, not minus them!

That has to be the wrong answer!
Title: Re: General Math Q+A Thread
Post by: RuiAce on April 01, 2018, 02:21:26 pm
I’m actually confused. How do you calculate the cumulative frequency from a stem and leaf plot?
The numbers less than or equal to 163 in that stem and leaf plot are
151, 151, 151, 152, 160, 160, 163, 163, 163, 163.

There are 10 numbers. So the cumulative frequency of 163 is 10.
Okay, so this is the solution on the answers for a past trial paper I've been doing, but I swear to god it's wrong - or I'm just really stupid. Can someone please confirm? My answer is waaay off this, and I swear I haven't done anything wrong because I've gotten the same answer three times. I don't understand why they've minused the a and the b when the formula clearly states you're supposed to add them?
Presumably, the area enclosed by the trapezium but excluding that triangle was meant to be shaded. Judging by the quality of the picture, it looks like that the shading disappeared when the image got scanned.

The question most likely only wanted the area of a "shaded" region. So if the shaded region was the trapezium without the triangle in the middle, then their working out is fine
Title: Re: General Math Q+A Thread
Post by: Lumenoria on April 02, 2018, 01:54:31 pm
Can someone please help me with the last 3 of question 8? I am literally lost. The answers are;
c. 9/100
d. 0.066
e. 0.624
I need working out aswell, because I literally have no clue how they've ascertained such answers and my exams are tomorrow.

Thankyou so much!!
Title: Re: General Math Q+A Thread
Post by: RuiAce on April 02, 2018, 02:18:09 pm
Can someone please help me with the last 3 of question 8? I am literally lost. The answers are;
c. 9/100
d. 0.066
e. 0.624
I need working out aswell, because I literally have no clue how they've ascertained such answers and my exams are tomorrow.

Thankyou so much!!



_________________________________________________

Title: Re: General Math Q+A Thread
Post by: Lumenoria on April 02, 2018, 06:37:37 pm



_________________________________________________



Omg thankyou so much, seriously!! This clarified things so much, thankyou!!
Title: Re: General Math Q+A Thread
Post by: joemassoud on April 04, 2018, 12:35:05 pm
Can someone please help me with this question
Title: Re: General Math Q+A Thread
Post by: RuiAce on April 04, 2018, 12:36:50 pm
Can someone please help me with this question

\begin{align*}A&=\pi r (r+s)\\ \frac{A}{\pi r}&= r + s\\ \frac{A}{\pi r} - r &= s\end{align*}
\[\therefore \boxed{s = \frac{A}{\pi r} - r} \]
Title: Re: General Math Q+A Thread
Post by: joemassoud on April 04, 2018, 12:50:14 pm
\begin{align*}A&=\pi r (r+s)\\ \frac{A}{\pi r}&= r + s\\ \frac{A}{\pi r} - r &= s\end{align*}
\[\therefore \boxed{s = \frac{A}{\pi r} - r} \]

Thank you soo much!

Just one more question, is there a 'rule of thumb' in regards to what you must do first when changing the formula of a subject.? (in a particular order)



Title: Re: General Math Q+A Thread
Post by: MAGGOT on April 04, 2018, 03:44:26 pm
Thank you soo much!

Just one more question, is there a 'rule of thumb' in regards to what you must do first when changing the formula of a subject.? (in a particular order)

in reverse of bodmas form
Title: Re: General Math Q+A Thread
Post by: Razeen25 on May 07, 2018, 08:10:53 pm
Hi,
Could someone please help me with this question? I asked my teacher but I still don’t understand it : (.

“James walked 2.8 km due west of home, then turned and walked on a bearing of 296° until he was 4.9 km from home. What is James’s bearing from home?”

The answer is 281°, but I keep getting 303° SMHH.
Title: Re: General Math Q+A Thread
Post by: RuiAce on May 07, 2018, 08:38:32 pm
Hi,
Could someone please help me with this question? I asked my teacher but I still don’t understand it : (.

“James walked 2.8 km due west of home, then turned and walked on a bearing of 296° until he was 4.9 km from home. What is James’s bearing from home?”

The answer is 281°, but I keep getting 303° SMHH.

(May need to click on the image.)
(https://i.imgur.com/EkGlefe.png)
Title: Re: General Math Q+A Thread
Post by: Razeen25 on May 07, 2018, 08:56:48 pm
(May need to click on the image.)
(https://i.imgur.com/EkGlefe.png)

YOU EXPLAINED THIS PERFECTLY. Thank you soo much!
Title: Re: General Math Q+A Thread
Post by: Lumenoria on May 09, 2018, 08:05:22 am
 15 and 16 please!
Title: Re: General Math Q+A Thread
Post by: RuiAce on May 09, 2018, 09:11:08 pm
15 and 16 please!

The reason why it makes no difference is because we haven't specified any conditions on who sits at the front or who sits at the back.


_________________________________________



Title: Re: General Math Q+A Thread
Post by: emilyygeorgexx on May 09, 2018, 10:42:54 pm
15 and 16 please!

If you are doing ordered combinations, you can make your life easier by using the permutations function on the calculator (shift, multiplication sign). If you are doing unordered combinations you can use the combinations function (shift, divide sign).
Title: Re: General Math Q+A Thread
Post by: RuiAce on May 09, 2018, 11:05:25 pm
If you are doing ordered combinations, you can make your life easier by using the permutations function on the calculator (shift, multiplication sign). If you are doing unordered combinations you can use the combinations function (shift, divide sign).
Whilst this is true, I don't think this is relevant for the questions provided. They don't involve selecting a certain amount of people out of a group for something here, they're just arranging every person present into positions.

Of course, for the section coming right up, combinations can be useful.
Title: Re: General Math Q+A Thread
Post by: Lumenoria on May 13, 2018, 09:59:32 am


The reason why it makes no difference is because we haven't specified any conditions on who sits at the front or who sits at the back.


_________________________________________





Omg you explained this perfectly, thankyou!!
Title: Re: General Math Q+A Thread
Post by: Lumenoria on May 18, 2018, 10:17:56 pm
2d? I swear I've done it the same way that the example has but my answer is completely off lol. Thank you!!
Title: Re: General Math Q+A Thread
Post by: RuiAce on May 18, 2018, 10:48:31 pm
2d? I swear I've done it the same way that the example has but my answer is completely off lol. Thank you!!
You should be able to consider the complement for this one. The opposite of winning at least one prize is winning no prizes.

So just do 1 - your answer from c).

(Otherwise, you need to add the probability of winning only 1st prize, or winning only 2nd prize, or winning both)
-------------------------------------------------
Having said that, if you want to compare it to the original example, please post that one up as well
Title: Re: General Math Q+A Thread
Post by: Lumenoria on May 23, 2018, 11:17:45 pm

You should be able to consider the complement for this one. The opposite of winning at least one prize is winning no prizes.

So just do 1 - your answer from c).

(Otherwise, you need to add the probability of winning only 1st prize, or winning only 2nd prize, or winning both)
-------------------------------------------------
Having said that, if you want to compare it to the original example, please post that one up as well
Oo I got it, thankyou so much man!! I never thought of it that way haha. Thanks again.
Title: Re: General Math Q+A Thread
Post by: Razeen25 on May 30, 2018, 09:01:32 pm
Hi, I’m not sure if this is a stupid question but it’s annoying me.

In Mathematics and Health, in the Least-squares regression line questions, I don’t understand how when you find the equation of the line, the y-intercept is completely different from the actual y-int on the line on the scatter plot. Like my textbook shows a line which has its Y-int at 4.84 (on the graph) but the equation for THAT line is ‘y = -0.1357x + 276.82’.

And when you do the working out the that equation is correct but IT DOESNT MAKE SENSE IF ALL THE VARIABLES ARE NO WHERE NEAR THE Y-INT. ugh. I asked my math teacher and he had no idea, so if someone understands this please help. Exam next week, thaank you!  :’)
Title: Re: General Math Q+A Thread
Post by: RuiAce on June 01, 2018, 12:08:22 pm
Hi, I’m not sure if this is a stupid question but it’s annoying me.

In Mathematics and Health, in the Least-squares regression line questions, I don’t understand how when you find the equation of the line, the y-intercept is completely different from the actual y-int on the line on the scatter plot. Like my textbook shows a line which has its Y-int at 4.84 (on the graph) but the equation for THAT line is ‘y = -0.1357x + 276.82’.

And when you do the working out the that equation is correct but IT DOESNT MAKE SENSE IF ALL THE VARIABLES ARE NO WHERE NEAR THE Y-INT. ugh. I asked my math teacher and he had no idea, so if someone understands this please help. Exam next week, thaank you!  :’)
Can you post the full question so that I have something more concrete to refer to?
Title: Re: General Math Q+A Thread
Post by: rh1A on June 05, 2018, 08:22:01 am
Hello, :)
Just a few questions about questions that i have about some data and scatter plots i have done for mathematics and health...
The questions are:
What does the gradient mean for each set of data?
Describe any correlation between the 2 variables for each of data.
For which group of countries (developed/developing) do you think Government spending on health has a greater impact on life expectancy?


Soo...what exactly should i include in each question? They are all worth 2 marks each.
Sorry if it doesn't make sense... ::)
Chrz.
Title: Re: General Math Q+A Thread
Post by: RuiAce on June 05, 2018, 08:49:02 am
Hello, :)
Just a few questions about questions that i have about some data and scatter plots i have done for mathematics and health...
The questions are:
What does the gradient mean for each set of data?
Describe any correlation between the 2 variables for each of data.
For which group of countries (developed/developing) do you think Government spending on health has a greater impact on life expectancy?


Soo...what exactly should i include in each question? They are all worth 2 marks each.
Sorry if it doesn't make sense... ::)
Chrz.
The answer to the first question is pretty much on the formula sheet

(https://i.imgur.com/j94CMNP.png)

As for the rest, it will depend entirely on what the data looks like.
Title: Re: General Math Q+A Thread
Post by: rh1A on June 06, 2018, 07:25:32 am
Hello i have no idea how to answer this question:

 Francis is to be administered 3000mg of medication through an IV drip. The solution through which it can be administered comes in two forms, 50mg per 5mL or 8mg per 5mL. In either case the drip will be delivered at a rate of 20 drips per minute and there are 5 drips per mL. Calculate how much quicker the stronger solution will take to deliver the 3000mg of medication.


Thanks...
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on June 06, 2018, 01:52:02 pm
Hello i have no idea how to answer this question:

 Francis is to be administered 3000mg of medication through an IV drip. The solution through which it can be administered comes in two forms, 50mg per 5mL or 8mg per 5mL. In either case the drip will be delivered at a rate of 20 drips per minute and there are 5 drips per mL. Calculate how much quicker the stronger solution will take to deliver the 3000mg of medication.


Thanks...

Hey there! So let me show you how to do it for the weaker solution.

First, we have 20 drips per minute, and 5 drips per mL. 5 goes into 20 four times - This means we will have 4mL/minute of solution going in, regardless of which we pick.

Now for the weaker solution, there are 8mg of medication per 5mL. We have 4mL, or 4/5 of the amount of solution. So, we also have 4/5 the amount of medication.



So we are getting 6.2mg of medication, per minute. How many minutes will it take to deliver 3000mg?



Try doing the same with the stronger solution to figure out how much quicker it will be! ;D
Title: Re: General Math Q+A Thread
Post by: kaustubh.patel on June 10, 2018, 08:51:28 pm
hey guys i might need some help with a question too. Part c im not getting the ans is S=0.9275M + 8.0041
Title: Re: General Math Q+A Thread
Post by: RuiAce on June 10, 2018, 09:03:23 pm
hey guys i might need some help with a question too. Part c im not getting the ans is S=0.9275M + 8.0041
The answers are using \(T\) and \(H\). Where are you getting \(S\) and \(M\)?
Title: Re: General Math Q+A Thread
Post by: BrittyG on June 23, 2018, 10:36:04 pm
Hi all,
This question was in my task 3 exam on Wednesday and has been racking my brain the past couple of days!! Someone help me out here pleaseeeee

'Three cards, 'K, Q, J' are faced down on a table.

One card is selected at random and replaced.

A second card is selected at random and replaced.

This experiment is repeated 45 times, what is the expected number of getting 2 Queens.'

I think in the exam I came to the conclusion of 5 but I have no idea how I got it or if it's right.
Title: Re: General Math Q+A Thread
Post by: RuiAce on June 23, 2018, 10:57:13 pm
Hi all,
This question was in my task 3 exam on Wednesday and has been racking my brain the past couple of days!! Someone help me out here pleaseeeee

'Three cards, 'K, Q, J' are faced down on a table.

One card is selected at random and replaced.

A second card is selected at random and replaced.

This experiment is repeated 45 times, what is the expected number of getting 2 Queens.'

I think in the exam I came to the conclusion of 5 but I have no idea how I got it or if it's right.
Well, if we include ordering then your events are KK, KQ, KJ, QK, QQ, QJ, JK, JQ, JJ (9 events), and they're all equally likely. So the probability of QQ is just 1/9, so when you multiply that by 45...
Title: Re: General Math Q+A Thread
Post by: BrittyG on June 23, 2018, 11:17:08 pm
So the probability of QQ is just 1/9, so when you multiply that by 45...
5!! Cheering!

Thank you for clearing that up :))
Title: Re: General Math Q+A Thread
Post by: Razeen25 on July 02, 2018, 12:28:20 am
I don’t know how to answer this question, could somebody please help? The answer is 64.
Title: Re: General Math Q+A Thread
Post by: jamonwindeyer on July 02, 2018, 12:40:58 am
I don’t know how to answer this question, could somebody please help? The answer is 64.

Hey! Here's a hint - Take the top left corner. There might be a dot there, there might not be. Two options. The one next to it might be there, it might not be. Two options there. So the top row, you'd have \(2\times2=4\) possibilities! See if you can keep the pattern going for the third, fourth, fifth and sixth dots to get 64 ;D
Title: Re: General Math Q+A Thread
Post by: Razeen25 on July 11, 2018, 09:13:57 pm
Hii, I'm really stuck on these 2 probability questions. Any help at all would be greatly appreciated!!
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 11, 2018, 09:21:41 pm
Hii, I'm really stuck on these 2 probability questions. Any help at all would be greatly appreciated!!
Q9 is probably best done by listing, as far as the General course goes:
KJA JKA AJK
KAJ AKJ JAK
We see that there are 4 favourable options, so the probability is 4/6, i.e. 2/3.



________________________________________

Do you know what a combination is? Because this is actually just \( \frac{4}{\text{52 choose 5}} \).
Title: Re: General Math Q+A Thread
Post by: Lumenoria on July 29, 2018, 02:05:39 pm
Hey,
How am I supposed to do the second question? Lol I feel like it's probably really obvious but I legit have been staring at it aimlessly for the longest time. I think the diagram is just kinda confusing
Title: Re: General Math Q+A Thread
Post by: RuiAce on July 29, 2018, 02:10:11 pm
Hey,
How am I supposed to do the second question? Lol I feel like it's probably really obvious but I legit have been staring at it aimlessly for the longest time. I think the diagram is just kinda confusing


Basically two applications just means use Simpson's rule twice.
Title: Re: General Math Q+A Thread
Post by: BrittyG on August 08, 2018, 12:43:32 pm
I feel like I've tried everything with this question, I looked at the answer and tried to work backwards too... Someone help a sister out pls

(Answers say B)
Title: Re: General Math Q+A Thread
Post by: RuiAce on August 08, 2018, 12:48:31 pm
I feel like I've tried everything with this question, I looked at the answer and tried to work backwards too... Someone help a sister out pls

(Answers say B)
At first glance I don't seem to get any of them actually...
I get an answer of \(-1.41\).

If we replace 34 numbers with 30 numbers I seem to get B incidentally.
Title: Re: General Math Q+A Thread
Post by: BrittyG on August 08, 2018, 01:38:08 pm
At first glance I don't seem to get any of them actually...
I get an answer of \(-1.41\).

That's what I kept getting too  ???, I thought I was going crazy or something
Title: Re: General Math Q+A Thread
Post by: RuiAce on August 08, 2018, 01:48:57 pm
That's what I kept getting too  ???, I thought I was going crazy or something
Well if we're both getting the same "wrong" answer I think we should assume that the question is wrong. :D
Title: Re: General Math Q+A Thread
Post by: rainyyydays on August 08, 2018, 11:28:09 pm
hey, know it's late! just having trouble with this q and can't find solutions... any help would be appreciated  :)

Title: Re: General Math Q+A Thread
Post by: fun_jirachi on August 09, 2018, 06:29:38 am
You just need to find the area of the lake and its a really big trek because of all the pieces. :'(
You're going to be using the base x height thing for area, and also h(a+b)/2 for the trapezium (assuming that it is, because i can't tell from the picture)
the maximum volume of the lake is equal to ((110*25)/2 + (120*30)/2 + 55(120+105)/2)*3.6 = 33705 m^3
now the lake is 80% full, so the water in the lake is equal to 26964 m^3 = 26964000L
the people of the town need 740*650 L /day = 481000 L per day
to find how many days they last w/o rain its 26964000/481000 = 56.058......
you round that down since they're not gonna last the 57th day with water usage
so they last 56 days
Title: Re: General Math Q+A Thread
Post by: rainyyydays on August 09, 2018, 07:36:19 am
legend  ;D
 thanks!
Title: Re: General Math Q+A Thread
Post by: rh1A on September 24, 2018, 05:07:29 pm
Hello,
Just need some help on the below questions from last years HSC...

A set of data has a lower quartile of 10 and an upper quartile of 16.
What is the maximum possible range for this set of data if there are no outliers?


A solid is made up of a sphere sitting partially inside a cone.
The sphere, has a radius of 4cm and sits 2cm inside the cone. The solid has a total height of 15cm.
What is the volume of the cone, correct to the nearest cm3?

Also, i've forgotten how to calculate correlation coefficient on the calculator....can someone pleasseee remind me how...

Thanks so much :)
Title: Re: General Math Q+A Thread
Post by: RuiAce on September 24, 2018, 09:04:11 pm
Hello,
Just need some help on the below questions from last years HSC...

A set of data has a lower quartile of 10 and an upper quartile of 16.
What is the maximum possible range for this set of data if there are no outliers?


Title: Re: General Math Q+A Thread
Post by: rh1A on September 25, 2018, 07:39:03 am
Quote
Recall from the formula sheet that outliers occur
if their score is less than
Q
L

1.5
×
I
Q
R
, which in your case is
10

1.5
×
6
=
1
or if their score is greater than
Q
U
+
1.5
×
I
Q
R
, which is
16
+
1.5
×
6
=
25


Thanks for tht  :) :) :)
Title: Re: General Math Q+A Thread
Post by: Razeen25 on October 11, 2018, 01:45:45 am
Hi,
In typical questions such as “Calculate the area of the annulus” where the question doesn’t specify “correct to the nearest metre” or something like that, what are we expected to round up to? Is it alright to round to 2 decimal points and add “(2 d.p.)” at the end?
Title: Re: General Math Q+A Thread
Post by: SEasternCry on October 11, 2018, 01:52:33 am
Hi,
In typical questions such as “Calculate the area of the annulus” where the question doesn’t specify “correct to the nearest metre” or something like that, what are we expected to round up to? Is it alright to round to 2 decimal points and add “(2 d.p.)” at the end?

Yes certainly! I've been doing that all the time and haven't lost a single mark for that. 2 dp should be the most appropriate.
Title: Re: General Math Q+A Thread
Post by: Razeen25 on October 11, 2018, 03:57:31 am
Yes certainly! I've been doing that all the time and haven't lost a single mark for that. 2 dp should be the most appropriate.

Ahh thank you! I too have been rounding up to 2dp, however I noticed the HSC answers seem to round to nearest unit instead so needed clarification, but yeah should be all goods!
Title: Re: General Math Q+A Thread
Post by: alole201 on October 20, 2018, 09:50:20 pm
need help with this math question ;)


A motor bike is moving at a steady speed. When the speed is 90km/h the bike consumes 5 litres of petrol for every 100 kilometres travelled.

a) the petrol tank holds 30 litres. how many kilometres can the bike travel on a full tank of petrol when its speed is 90km/h?

b) when the speed is 110km/h the bike consumes 30% more petrol per km travelled. calculate the number of litres per 100 kilometres consumed when the bike travels at 110 km/h.
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 20, 2018, 09:57:37 pm
need help with this math question ;)


A motor bike is moving at a steady speed. When the speed is 90km/h the bike consumes 5 litres of petrol for every 100 kilometres travelled.

a) the petrol tank holds 30 litres. how many kilometres can the bike travel on a full tank of petrol when its speed is 90km/h?

b) when the speed is 110km/h the bike consumes 30% more petrol per km travelled. calculate the number of litres per 100 kilometres consumed when the bike travels at 110 km/h.

Hence 600km.
________________________________________________

Hence 6.5L
Title: Re: General Math Q+A Thread
Post by: zanibalh on October 21, 2018, 07:34:44 pm
Hey guys - just a couple of questions from the 2011 paper; i tried looking over the answers but just still a bit confuzzled tbh.

Thankyou so much in advance!!
Title: Re: General Math Q+A Thread
Post by: fun_jirachi on October 21, 2018, 08:03:40 pm

So Q18 is A.

i) Figure four is four rooves, two sticks down either side, then four across the bottom, using 14 sticks in all.
ii) You need 3n+2 sticks for the nth figure (just by finding a pattern) so sub in n=100 and you get 302 sticks.
iii) solve 3n+2=543 as per the rule. The answer is no since you have to have an integer number for n, as you can't have a non-integer number for the figure number. I'd suggest starting with 3n+2=543, then working down from there, reasoning why n has to be an integer :)

So the circumference of the earth at the equator is

and there are 360 degrees around there earth. Technically yes you can add 109 and 160 to get the distance, but it asks for the shortest distance, so you take the short side, which is 91 (from 360-(109+160)).
So you get that the shortest distance is

which is equal to whatever, punch it into the calculator

for the next one, realise that 48 degrees west of 160 will cut past 180, so it's actually something degrees east. you'll eventually get to 152 degrees east and 4 degrees south.

Last question :)
If the median score of 9 is 7, that means there are four scores below it, four above, with the 5th score being seven. Adding two to both sides (two numbers bigger, two numbers smaller) doesnt actually change the median since it's still in the middle positionally in terms of magnitude. Therefore, the answer is B, 7.

:)


Title: Re: General Math Q+A Thread
Post by: joemassoud on October 22, 2018, 08:47:03 am
Well if we're both getting the same "wrong" answer I think we should assume that the question is wrong. :D

Hey Guys,

So I thought I should have a go at the question seeing that no one was getting the "correct answer - B." However, I think the answer is also -1.41.

Working Out:

(2/34) x $10 = $0.5882....

$2 - $0.5882.... = -1.41
Title: Re: General Math Q+A Thread
Post by: alole201 on October 22, 2018, 07:42:51 pm
help with this question  8)

The three sides of a triangle are in the ration 1:3:5. The longest side of the triangle is 16.2 mm. What is the perimeter of the triangle?
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 22, 2018, 08:06:15 pm
help with this question  8)

The three sides of a triangle are in the ration 1:3:5. The longest side of the triangle is 16.2 mm. What is the perimeter of the triangle?


Note that \(9.72\) was obtained from doing \(3.24 \times 3\).
Title: Re: General Math Q+A Thread
Post by: fun_jirachi on October 22, 2018, 08:06:28 pm
Hey there!

Looking at the ratios, there are 9 parts that are split evenly. All you've really got to do is see that the 16.2 is five-ninths of the whole perimeter, so just multiply 16.2 by 9/5 to get your answer. You should get 29.16 :)
Title: Re: General Math Q+A Thread
Post by: rh1A on October 24, 2018, 07:14:30 am
Help with attached question pleeasse :)
danke...
Title: Re: General Math Q+A Thread
Post by: RuiAce on October 24, 2018, 10:19:01 am
Help with attached question pleeasse :)
danke...

Title: Re: General Math Q+A Thread
Post by: ishhhyyyaaa on October 24, 2018, 07:00:31 pm
hey,

can someone please explain these questions to me?

thanks alot!!
Title: Re: General Math Q+A Thread
Post by: fun_jirachi on October 24, 2018, 07:42:58 pm
Hey there!

For the first one, notice that all the units in the question and answers are in SI units! It's not specifically maths, but 1 watt (W) is equal to 1 Joule per second (Js-1), so the answer is C.

For the second and third one, I've both downloaded and expanded the pictures and I still can't read them! Do you happen to have a clearer picture, because if so I'd be glad to help you.

For the last one, its just knowing that tera- means roughly 1012. Knowing that there are 1024 bytes in a megabyte and 1024 megabytes in a gigabyte and so on as well as that 8 bits make one byte, 23(for the bits)x10244 (since one terabyte is roughly 1012, or think about it as 1024 and going up 4 levels). 1024 = 210 so using indice laws you get that there are 243 bits in 2 terabytes.

Hope this helps!

Title: Re: Standard Math Q+A Thread
Post by: jamonwindeyer on November 10, 2018, 04:25:23 pm
Hey! With HSC exams now over, we are now doing the new version of General Maths - Standard Maths! Almost everything about the old course has stayed the same, so everything from before this point is still super useful. Feel free to have a scroll back! ;D
Title: Re: Standard Math Q+A Thread
Post by: Equilibrium on November 18, 2018, 08:17:36 pm
Hi! This is my second post on here, I'm in Year 10 & about to transition into Year 11. I've already elected to undertake General Maths because I know how important it is to learn... But I'm currently reading a textbook for next year & cannot comprehend what I'm reading. I've never been good at maths, always easily getting better marks in my language & humanities based subjects.
I'm too embarrassed to ask a teacher about it, I don't want someone I might face every day thinking I'm dumb...
Would anyone be able to help me decipher this? 😅

“The inverse operation to exponentiation is logarithms, and as exponents aren't commutative like addition and multiplication are, there are two possible inverses, the other being surds.
The square root of (x squared) equals x, and so in that way the root is the inverse operation, but then there's also this (the first equation has been shifted up by 1, but both essentially give the graph for y=x, despite the second equation including an exponent).”

There's a graph diagram underneath.


Title: Re: Standard Math Q+A Thread
Post by: S200 on November 18, 2018, 08:40:15 pm
I don't fully get what it's saying myself (maybe if you uploaded a picture of the graphs we could help better?) but I'll try to explain a little.
“The inverse operation to exponentiation is logarithms, and as exponents aren't commutative like addition and multiplication are, there are two possible inverses, the other being surds.
\(y=2^x\) is an exponential, and you would get the inverse by placing the \(y\) where the \(x\) is.
Solving for \(y\) requires using a logarithm.
The Basic form of a logarithm
\(y=a^x \therefore \log_a {y}=x\)
Eg: \(64=2^x \quad \log_2 {64} = x, \quad x=8\)
So, when solving the aforementioned equation, we would find that the inverse function to \(y=2^x\) is \(y=\log_2 {x}\).

We can visually see that this is correct when we graph it, by inserting the line \(y=x\), showing that the reflection is symmetrical about this line.


By commutative, the textbook is saying that unlike addition and multiplication, where \(1+2=2+1\) and \(a\times b=b\times a\), an exponential cannot be the so easily switched around...

i.e: \(2^x \ne x^2\)


Please reply if anything doesn't make sense, and I'll try to help more.
Also, Welcome to AN... :D
Title: Re: Standard Math Q+A Thread
Post by: ChloeWalker on January 15, 2019, 01:43:51 pm
Hi, I'm not too sure if this is where I can ask this, if it's not if someone could redirect me that would be great!

It's a standard maths question:

"Calculate the future value, to the nearest cent.  a) Present value of $680 invested for 4 years at 5% p.a. compounded biannually"
the answer in the book is $828.51 (Cambridge maths book)

This is what I did and if someone can spot the flaw please let me know!!
P = 680
r = 10%
period = 2

Thankkss!!!!
Title: Re: Standard Math Q+A Thread
Post by: RuiAce on January 15, 2019, 01:56:28 pm
Hi, I'm not too sure if this is where I can ask this, if it's not if someone could redirect me that would be great!

It's a standard maths question:

"Calculate the future value, to the nearest cent.  a) Present value of $680 invested for 4 years at 5% p.a. compounded biannually"
the answer in the book is $828.51 (Cambridge maths book)

This is what I did and if someone can spot the flaw please let me know!!
P = 680
r = 10%
period = 2

Thankkss!!!!
It's a trap in the wording.

For varying reasons that I never quite understood myself, "biannually" actually means compounded twice every year, as opposed to once every two years. Which is equivalent to saying that the interest is actually compounded semi-annually. So you should have \(r = 2.5\%\) and \( \text{number of periods} = 8\), giving \( 680(1.025)^8\) as your answer.
Title: Re: Standard Math Q+A Thread
Post by: alole201 on February 08, 2019, 10:30:41 pm
Hi everyone!!

I was wondering if anyone could help me with explaining bearings (true, compass etc.). I've been confused for the past few days about it and i was hoping for some clarification!

Thanks  :o
Title: Re: Standard Math Q+A Thread
Post by: ChloeWalker on March 03, 2019, 08:08:03 pm
Hi can anyone help me out with this question:

"How long will it take to pay off a credit card debt of $1000 if the annual interest rate is 18.5% and you only make the minimum payment each month (assuming no other transactions)? How much interest will you pay?"
Title: Re: Standard Math Q+A Thread
Post by: matthewwu2003 on July 10, 2019, 04:25:30 pm
Hi everyone!!

I was wondering if anyone could help me with explaining bearings (true, compass etc.). I've been confused for the past few days about it and i was hoping for some clarification!

Thanks  :o

There are two types of bearings, True Bearing and Compass Bearing.

Compass Bearing specifies the direction in terms of the four cardinal directions: North (N), South (S), East (E), West (W). All other directions are indicated by the deviation from North (N) or South (S) towards the East (E) or West (W).
For Example: N35E, S41W, N23W

True Bearing specifies the direction by its deviation from North. It is measured clockwise from North and expressed as a three digit number.
For Example: 035T, 056T, 120T

Below I have attached some diagrams for your reference.
Title: Re: Standard Math Q+A Thread
Post by: LoneWolf on July 18, 2019, 06:01:11 pm
Hey I know this is standard and I do mathematics (year 11) but i have forgotten the null factor law. Can someone explain how i solve dydx=0 to find x & y coordiates in view of finding where any points where the tangent is horizontal:

y= (x^2-1)^3
dy/dx = 6x(x^2-1)^2
dy/dx = 0
....
....
....

& i am confused from here!
Title: Re: Standard Math Q+A Thread
Post by: fun_jirachi on July 18, 2019, 08:17:48 pm
Hey there!

Totally okay to post in the 2U thread btw :)

Basically the null factor law states that if at least one of the factors (in this case of the given polynomial) of some real number is zero, then the product is zero. Conversely, if all the factors are nonzero, then the product is nonzero.

Take for example the following polynomial


In your case:

ie. there are horizontal tangents at (0, -1), (1, 0) and (-1, 0)

Hope this helps :)
Title: Re: Standard Math Q+A Thread
Post by: LoneWolf on July 19, 2019, 09:25:05 am
Ok sweet.
Just 1 thing did you mean (-1,0) rather than (-1,-8)?
Title: Re: Standard Math Q+A Thread
Post by: fun_jirachi on July 19, 2019, 11:32:07 am
Ok sweet.
Just 1 thing did you mean (-1,0) rather than (-1,-8)?

Yep, thanks for the pick-up :) Post has been edited to reflect that :D
Title: Re: Standard Math Q+A Thread
Post by: alole201 on July 25, 2019, 05:29:13 pm
Hi!! Can someone please help me with this multiple choice question?

An experiment has three distinct outcomes, A, B and C. Outcome A occurs 50% of the
time. Outcome B occurs 23% of the time.

What is the expected number of times outcome C would occur if the experiment is
conducted 500 times?

A. 115
B. 135
C. 250
D. 365
thank you!
Title: Re: Standard Math Q+A Thread
Post by: fun_jirachi on July 25, 2019, 06:04:54 pm
Hey there!

If n distinct outcomes are possible for some experiment, it's implied that the sum of the probabilities a1+a2+a3+...+an = 1, where ak is one of the distinct outcomes' probabilities, where k is an integer such that 0<k<=n.

As such, in this question, we have three distinct outcomes whose probabilities must sum to 1, or 100%. Given the other two probabilities, we can subtract them from 100%, and thus we obtain the fact that C occurs 27% of the time. Hence, if the experiment is conducted 500 times, outcome C will occur in 27% of 500 times, ie. the answer should be B, 135.

Hope this helps :)
Title: Re: Standard Math Q+A Thread
Post by: dani01 on August 06, 2019, 05:24:13 pm
Hi I'm having a bit of trouble wrapping my head around percentage error/measurement type questions (I know they are practically easy) but for example what would be the absolute error of the number 5.54mm. the formula sheet has 1/2 x precision but how do I find the precision? is it just .05 and then i half that to find the absolute error. so then if i have a number 7.89 the absolute error is the exact same? i think that is what I don't understand.
I get how to find the percentage error of the number but when I type it in to my calculator how do I know where to round off the percentage?

Hope this all makes sense    :) :)
Title: Re: Standard Math Q+A Thread
Post by: RuiAce on August 06, 2019, 05:53:36 pm
Hi I'm having a bit of trouble wrapping my head around percentage error/measurement type questions (I know they are practically easy) but for example what would be the absolute error of the number 5.54mm. the formula sheet has 1/2 x precision but how do I find the precision? is it just .05 and then i half that to find the absolute error. so then if i have a number 7.89 the absolute error is the exact same? i think that is what I don't understand.
I get how to find the percentage error of the number but when I type it in to my calculator how do I know where to round off the percentage?

Hope this all makes sense    :) :)
The precision is basically just how far you go with decimal points. If your measurement is 5.54mm, then they are precise up to the nearest 0.01mm. So the absolute error is then one half of this, i.e. 0.005mm.

With 7.89, sure if you assume that it's also measured in mm. If it were in cm, then your absolute error would be 0.005cm.

I think you get told how far to round with your percentage error.
Title: Re: Standard Math Q+A Thread
Post by: dani01 on August 11, 2019, 03:08:42 pm
I've been doing some past papers and questions which always come up are those with combinations etc. Was this part of the old syllabus or do I have to know this because I have never done these in class or seen the formulas which are shown in the answers.
Title: Re: Standard Math Q+A Thread
Post by: Mia-lexa on September 29, 2019, 01:35:13 pm
I've been doing some past papers and questions which always come up are those with combinations etc. Was this part of the old syllabus or do I have to know this because I have never done these in class or seen the formulas which are shown in the answers.

I think you're referring to probability? For example, you would find questions like: 'A bag contained 4 blue marbles, 3 red marbles and 2 green marbles. If Bob drew one marble and then drew another one. What is the probability that he will draw two marbles of the same colour?'
If this is the type of question you are talking about and you are having trouble understanding it or solving it, I would recommend revising it and asking for help from your math teachers. There are also papers you can find online with worked examples that can help you work closely on a specific subject as such. Probability is part of our current syllabus so it would definitely be worth revising before your final exams. Good luck!  ;)
Title: Re: Standard Math Q+A Thread
Post by: dani01 on October 01, 2019, 11:08:33 am
I think you're referring to probability? For example, you would find questions like: 'A bag contained 4 blue marbles, 3 red marbles and 2 green marbles. If Bob drew one marble and then drew another one. What is the probability that he will draw two marbles of the same colour?'
If this is the type of question you are talking about and you are having trouble understanding it or solving it, I would recommend revising it and asking for help from your math teachers. There are also papers you can find online with worked examples that can help you work closely on a specific subject as such. Probability is part of our current syllabus so it would definitely be worth revising before your final exams. Good luck!  ;)

Hey its all good I was talking about something called permutations and I checked with my teacher a while back and Its nothing I've got to worry about since it is part of the old sylllabus! thanks though
Title: Re: Standard Math Q+A Thread
Post by: LoneWolf on January 07, 2020, 08:07:17 am
Hey People,

Just a quicky.

Should i use 'sample' or 'population' standard deviation when they just ask for 'standard deviation'?
Also, it may be beneficial if some1 could tell me the difference!

Thanks everybody
Title: Re: Standard Math Q+A Thread
Post by: RuiAce on January 07, 2020, 04:20:29 pm
Hey People,

Just a quicky.

Should i use 'sample' or 'population' standard deviation when they just ask for 'standard deviation'?
Also, it may be beneficial if some1 could tell me the difference!

Thanks everybody
The difference is really in what a sample is. The population standard deviation is the actual standard deviation. 'Population' refers to every object that you have.

A 'sample' is when you take only some of the objects out of the entire population. It's important because, in practice statisticians are not going to be able to survey everyone in the population. Only a small bunch will respond, and they are the sample. But the sample has to be used to deduce all statistical conclusions.

The sample standard deviation is used when you're interested in the SD of a sample. (In the real world, it's used to estimate the population standard deviation.)

I asked the standard math team and they've told me that generally you should use the population SD. Presumably, this would be because you're usually given information about the entire population. Or at the very least, from my understanding, you should assume that's the case when you're given no further info.
Title: Re: Standard Math Q+A Thread
Post by: LoneWolf on January 07, 2020, 09:03:09 pm
Ripper thanks RuiAce

So helpful to have another POC when your school teacher doesnt respond ;D
Title: Re: Standard Math Q+A Thread
Post by: LoneWolf on January 08, 2020, 10:16:41 am
Hello People,

Does anyone know how to activate the pearsons correlation coefficient mode on a CASIO fx-82AU PLUS II?
Title: Re: Standard Math Q+A Thread
Post by: LoneWolf on January 08, 2020, 10:45:54 am
Have since worked it out.

1. Turn on right stat mode
 - Mode, 2:stat, 2:A+BCX
2. Enter Data (independent variable x-axis)
- Enter data, AC.
3. Extract Data
- Shift, 1:Stat, 5:Reg, 3:r
Title: Re: Standard Math Q+A Thread
Post by: LoneWolf on January 08, 2020, 12:12:12 pm
Another question  ;D ;D ;D

Why doesn't correlation imply causation?
It is simple but i am getting very muddled! i.e. why, doesnt the data prove just that?
Title: Re: Standard Math Q+A Thread
Post by: RuiAce on January 08, 2020, 05:08:11 pm
Another question  ;D ;D ;D

Why doesn't correlation imply causation?
It is simple but i am getting very muddled! i.e. why, doesnt the data prove just that?
There's actually a Wikipedia article on this. It's a very famous statistical concept.

To summarise it though, the WIkipedia article presents several counter-examples to disprove that "correlation must imply causation". The Wikipedia article also suggests reasons why there may be no causation between the two variables you're modelling,

If you're not bothered to read the entire Wikipedia page, this is perhaps one of the examples I feel illustrates the point the most..

Quote
As ice cream sales increase, the rate of drowning deaths increases sharply.
Therefore, ice cream consumption causes drowning.

This example fails to recognize the importance of time of year and temperature to ice cream sales. Ice cream is sold during the hot summer months at a much greater rate than during colder times, and it is during these hot summer months that people are more likely to engage in activities involving water, such as swimming. The increased drowning deaths are simply caused by more exposure to water-based activities, not ice cream. The stated conclusion is false.

In short, here, the two variables seemed highly correlated, but not because one caused the other. But rather, there was a hidden third variable that was causing both to increase.

The Wikipedia article shows that in general, this might not be the only reason that disproves "correlation implies causation". But this reason seems to be the easiest to understand, in my opinion.
Title: Re: Standard Math Q+A Thread
Post by: LoneWolf on January 08, 2020, 08:14:22 pm
Ah smashing.
Thanks again.
Title: Re: Standard Math Q+A Thread
Post by: LoneWolf on January 23, 2020, 08:25:52 am
Another One' 8)

Is hamiltonian graphs part of the syllabus, it is in my cambridge textbook (genny) and im not sure if its worth stdying. it says ENRICHMENT.

THANKS
Title: Re: Standard Math Q+A Thread
Post by: RuiAce on January 23, 2020, 10:14:37 am
You can see from the syllabus that it is NOT in the syllabus.

Your teacher may be able to bend the grounds a little and put it inside an assignment task. But it is not in the syllabus and thus should never appear in an exam.
Title: Re: Standard Math Q+A Thread
Post by: LoneWolf on January 23, 2020, 10:28:41 am
legend thats awesome.

thanks again.
Title: Re: Standard Math Q+A Thread
Post by: LoneWolf on April 20, 2020, 08:26:49 am
Hey people
Struggling with this!
Any suggestions?
Title: Re: Standard Math Q+A Thread
Post by: StudyNinja on April 25, 2020, 02:30:01 pm
Hey people
Struggling with this!
Any suggestions?


Interest is compounded monthly but quoted per annum so first convert interest rate to monthly:
Monthly interest rate will be = 7.4% / 12 = 0.616667%

Part (a) asks for future value after 4 years (4 years have 48 months):
Using future value formula: 16400 x (1 + 0.616667%)^48 = 22,029

Regarding part (b), I am unclear if it is asking compound interest earned after 4 years or after 6 years. I am assuming it is continuation of part (a) and asking compound interest earned after 4 years in which case interest earned will simply be Future value after 4 years - Initial value of investment
22029 - 16400 = 5,629

Hope this helps
Title: Re: Standard Math Q+A Thread
Post by: LoneWolf on April 26, 2020, 08:48:57 am
Thanks for that dude. that was quite easy!
Title: Re: Standard Math Q+A Thread
Post by: frodoyo on June 22, 2020, 07:52:47 pm
hi everyone,

I'm really stuck on this question about network diagrams. I tried drawing one out but I'm not too sure if my diagram is correct. For part b, I don't see how changing (I) will affect (J), so could someone please lend a hand?

thank you!
Title: Re: Standard Math Q+A Thread
Post by: RuiAce on June 28, 2020, 05:55:14 pm
hi everyone,

I'm really stuck on this question about network diagrams. I tried drawing one out but I'm not too sure if my diagram is correct. For part b, I don't see how changing (I) will affect (J), so could someone please lend a hand?

thank you!
I just tried part a and I obtained the exact same network, with the exact same EST and LST times. So I think you should be all good.

For part b, it's very much possible that it doesn't. But potentially you might cut down on the project time here. I would suggest re-computing all the ESTs and see what the new completion time is. Note that because you're only interested in the completion time, you don't have to go back and calculate all the LSTs again the second time round.

Edit: Oh dear, sorry for the delay in reply! I've had a pretty busy week.
Title: Re: Standard Math Q+A Thread
Post by: LoneWolf on July 07, 2020, 05:54:12 pm
Any idea's why my answer of 1297.1 is wrong?
textbook says that it should be 1330?
Title: Re: Standard Math Q+A Thread
Post by: aakriti_04 on July 15, 2020, 11:31:23 am
Hi,

Maths I wouldn't say is my weakest, but making careless mistakes lowers my marks significantly. Where I could have gotten over 95%, I get an 80%. Every exam I make at least over 5 silly or careless mistakes or calculator mistake. This has really lowered my confidence in the subject. It feels now as if I can't do it anymore. Ands not even my carelessness anymore, its my stress. It overtakes me before I even begin my exam. How can I cut on the stress, and motivate myself that I can do it.
Title: Re: Standard Math Q+A Thread
Post by: aakriti_04 on July 28, 2020, 05:24:37 pm
Hey,
I'm currently in year 11 and I wouldn't say I'm struggling in standard maths at all. But I definitely think I'm capable of more and can do so much better.
The problem is my pre-exam stress and constantly making silly mistakes. It doesn't pain me loosing marks for questions I genuinely found difficult than it does for making careless mistakes. And whats worse is every time I finish an exam, I can count upon my fingers every mark I lost due to some silly mistake I might have made, that I just realize after the exam.
There are times I could genuinely get over 95% easily, but I end up with a 80% cause of all the silly mistakes. I'm really unsure of how to stop making those mistakes. I usually feel like I'm having nervous breakdowns during maths exams and cannot seem to pick up the mistakes. Maths is one subject I spend the most time studying for (to be quite honest). Yet, it doesn't pay off, and I don't get the marks I need. How can I really cut down on the silly mistakes. What are the best exam techniques (maths in particular) that I could use to overcome this. This isn't just one maths exam that it happens, its all of them now and I want to come out of this quickly as possible.

Thank you,
Title: Re: Standard Math Q+A Thread
Post by: maddycalvert on October 09, 2020, 06:01:31 pm
Hello,
I often read the ATAR notes forum but I've never made a post on it. Since it's the holidays I didn't want to email my maths teacher for help, I've been doing HSC past papers for maths standard and I am confused on how to convert when using KwH and watts, I know there is some kind of conversion involved.

The question I am working on is from the 2018 past paper:

"Every day, a 1200-watt microwave oven is used for 45 minutes at 40% power. Electricity is charged at $0.25 per kWh.
What is the cost of running this microwave for 180 days?"

additional question I have worked through a lot of HSC past papers, where are some more places I cold find more maths questions to practice?
Title: Re: Standard Math Q+A Thread
Post by: fun_jirachi on January 20, 2021, 05:31:48 pm
Totally missed this somehow (and only noticed it now :(), sorry for the late reply! Hopefully, you're still around and this is still a relevant response😞

The 1200 watt microwave only uses 40% of its power - ie. 480 watts = 0.48 kilowatts. It uses this for 45 minutes = 0.75 hours.

A kilowatt-hour is a unit of energy. One kilowatt-hour of energy is 'produced' when one kilowatt of power is applied for one hour.
We multiply the power by the time ie. 0.48 kW * 0.75h = 0.36 kWh. The microwave uses this amount of energy every day for 180 days, so it uses a total of 64.8 kWh of energy over that time, which costs 64.8kWh * $0.25/kWh = $16.20.

If you've worked through a lot of past papers, you could also look for student repositories supplied by your school - they often have past papers from your school and perhaps other schools that your teacher/faculty might have procured. otherwise external books are often a good resources. Redoing questions with different numbers is a bit desperate but is also a good enough way to get even more practice in.
Title: Re: Standard Math Q+A Thread
Post by: anonymous_bean on May 01, 2021, 05:51:16 pm
Hi this is my first time posting so I hope I’m posting it in the right place.
I’ve been working on some maths questions but I wasn’t sure if I was doing them right. I think my main problem is understanding what the question wants.
For the first question I did. There was a description of how Anna walked around and I had to draw a diagram matching this description. Using the diagram drawn I had to determine b) the distance that Anna walked (using a ruler I measured the hypotenuse of the triangle formed). And I got b = 6.5cm
For part c) I used Pythagoras theorem to determine the distance that Anna walked. And I got 5.8 cm

d)      What is the difference between them? I think its 6.5 – 5.8 = 0.7
e)      Determine the difference as a percentage of the calculation from c) Round the percentage to the nearest whole number. I got confused about this question.
Is it just 6.5/5.8 x 100 = 112
 
Title: Re: Standard Math Q+A Thread
Post by: fun_jirachi on May 02, 2021, 01:29:22 pm
Not quite sure what you want to do for the first question, but for the second question that seems about right. It might be easier in future to provide the actual question (context is always important) instead of paraphrasing it.

Definitely posting it in the right place (if this is for Maths Standard?) so don't worry about that ;D
Title: Re: Standard Math Q+A Thread
Post by: anonymous_bean on May 02, 2021, 06:07:12 pm
Awesome. Thank you for your help :)
Here’s the actual question I was referring to. I hope it helps :)

Spoiler

Title: Re: Standard Math Q+A Thread
Post by: fun_jirachi on May 02, 2021, 07:54:27 pm
Basically for d)i) - you need to take the answer from c) and subtract it from the answer from b). If you're correct, d)i) should be the equivalent of 6.5-5.8 = 0.7 in metres based on the scale you used. This is because you can't use the measurements from your diagram - you're asked for the distance Kate walked, not the distance Kate walked on the diagram.

For d)ii), you need to calculate the percentage difference. Percentage difference is calculated by \(\frac{\text{error margin}}{\text{actual value}} \times 100\). Take your answer from d)i) and divide it by the actual distance Kate walked (ie. your answer from part c) ) to get your final answer.

Hope this clears things up :D
Title: Re: Standard Math Q+A Thread
Post by: anonymous_bean on May 03, 2021, 02:14:30 pm
That makes sense. Thank you for your help   :)

I was hoping to have some help with this question as well please. I think I’m right for part a. But I can’t think of how to do part b?
Title: Re: Standard Math Q+A Thread
Post by: fun_jirachi on May 03, 2021, 03:22:55 pm
Consider what happens if you divide a regular hexagon into six regular triangles.

- Can you determine what type of triangle it is?
- Can you then determine each angle/side of the triangle?

Alternatively, consider also that there are six stakes around a point. Remember that angles around a point add up to 360 degrees, and hence you should be able to find the angle between two stakes and use the cosine rule to find the last side.

Title: Re: Standard Math Q+A Thread
Post by: anonymous_bean on May 03, 2021, 04:10:40 pm
Oh so basically because there are essentially 6 equal triangles. The angle I would need would just be 360/6  = 60

And the side I need is basically
A^2 = 2.4^2  + 2.4^2 -2 (2.4)(2.4)cos 60. Is that right?

Thank you so much for your help. I feel like I just had a light bulb moment. I thought I had to use the polygon degree formula. And for some reason why head went blank about what the cosine rule was called.  ;D


Title: Re: Standard Math Q+A Thread
Post by: fun_jirachi on May 03, 2021, 04:20:47 pm
That would be correct :)

I thought I had to use the polygon degree formula. And for some reason why head went blank about what the cosine rule was called.  ;D

Well, you can - but it's a lot harder to navigate that way. If you're particularly good with geometry using the cosine rule is also unnecessarily complicated. Point is, there are loads of different ways suited to different people to get the same correct answer.
Title: Re: Standard Math Q+A Thread
Post by: anonymous_bean on May 03, 2021, 05:21:17 pm
Thank you again for the help. Otherwise I would still be thinking about what to do or even where to start  ;D