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June 22, 2021, 05:40:23 am

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#### LoneWolf

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##### Re: Standard Math Q+A Thread
« Reply #675 on: January 23, 2020, 10:28:41 am »
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legend thats awesome.

thanks again.
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#### LoneWolf

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##### Re: Standard Math Q+A Thread
« Reply #676 on: April 20, 2020, 08:26:49 am »
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Hey people
Struggling with this!
Any suggestions?
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#### StudyNinja

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##### Re: Standard Math Q+A Thread
« Reply #677 on: April 25, 2020, 02:30:01 pm »
+1
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

#### LoneWolf

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##### Re: Standard Math Q+A Thread
« Reply #678 on: April 26, 2020, 08:48:57 am »
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Thanks for that dude. that was quite easy!
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#### frodoyo

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##### Re: Standard Math Q+A Thread
« Reply #679 on: June 22, 2020, 07:52:47 pm »
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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!

#### RuiAce

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##### Re: Standard Math Q+A Thread
« Reply #680 on: June 28, 2020, 05:55:14 pm »
+4
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.
« Last Edit: June 28, 2020, 05:57:39 pm by RuiAce »

#### LoneWolf

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##### Re: Standard Math Q+A Thread
« Reply #681 on: July 07, 2020, 05:54:12 pm »
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Any idea's why my answer of 1297.1 is wrong?
textbook says that it should be 1330?
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#### aakriti_04

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##### Re: Standard Math Q+A Thread
« Reply #682 on: July 15, 2020, 11:31:23 am »
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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.

#### aakriti_04

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##### Re: Standard Math Q+A Thread
« Reply #683 on: July 28, 2020, 05:24:37 pm »
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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,

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##### Re: Standard Math Q+A Thread
« Reply #684 on: October 09, 2020, 06:01:31 pm »
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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? #### fun_jirachi • MOTM: AUG 18 • Moderator • Forum Leader • Posts: 947 • All doom and Gloom. • Respect: +613 ##### Re: Standard Math Q+A Thread « Reply #685 on: January 20, 2021, 05:31:48 pm » +3 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.
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#### anonymous_bean

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##### Re: Standard Math Q+A Thread
« Reply #686 on: May 01, 2021, 05:51:16 pm »
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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

« Last Edit: May 04, 2021, 10:02:55 am by anonymous_bean »

#### fun_jirachi

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##### Re: Standard Math Q+A Thread
« Reply #687 on: May 02, 2021, 01:29:22 pm »
+2
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
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#### anonymous_bean

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##### Re: Standard Math Q+A Thread
« Reply #688 on: May 02, 2021, 06:07:12 pm »
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Awesome. Thank you for your help
Here’s the actual question I was referring to. I hope it helps

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« Last Edit: May 04, 2021, 10:01:30 am by anonymous_bean »

#### fun_jirachi

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##### Re: Standard Math Q+A Thread
« Reply #689 on: May 02, 2021, 07:54:27 pm »
+1
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
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