VCE General & Further Maths Question Thread!

[TheCommando]

I had this exact same question on my sac.
so you do
17.1%-(8.1+0.93*18.4%)
=-8.112x-8.1

I had this exact same question on my sac.
so you do
17.1%-(8.1+0.93*18.4%)
=-8.112x-8.1

I dont know what the regression line is since i dont have the data but whatever it is you put the 1990 obesity rate in the x.
As the x means the explanatory variable
And the 1990 obesity rate is used to predict the 2010 obesity rate oddly

[Maya24]

Also where  did you get the 8.1+0.93 bit?
my least sq regression line equation was y=6.24+0.993x
with y being twentyten and x being 1990

My least squares regression was 8.1+0.93*1990.

[Maya24]

Thank you so much legit lifesaver! dont know of this is too much of a ask but im so lost, what would you say for the interpt part of the question
? thanks again all good if you can't answer xxxx

The way my teacher interepreted it was 2010 is expected to be 8.1% for a 0% in 1990

[pmmenotes]

for working out the vertical intercept i did 17.1%(6.24+0.993x18.4%)
=-7.4
would this be correct?

Also for the residual question i did
original=17.1%
predicted=6.24+0.993(18.4)
=24.5
residual=actual-predicted
=17.1-24.5=-7.4

Got the same answer for both? feel like I've made a mistake somewhere?


---

"Comment on the improvement or otherwise of each of the transformed equations compared to the original equation (y=6.24+0.993x) . Use mathmatical reasoning to support your comments"

Ok so i found that the orginial equation y=6.24+0.993x had a higher r2 value than the others it was 0.800 and th other transformed questions y2=0.57
logx=0.53
and 1/x=0.26

so based on this the orginal is an imporvment but im not sure on the wording or how to explain this?  Anyone know how i would go about it?

Mod Edit [Aaron]: Merged double post again.

[TheCommando]

for working out the vertical intercept i did 17.1%(6.24+0.993x18.4%)
=-7.4
would this be correct?

Also for the residual question i did
original=17.1%
predicted=6.24+0.993(18.4)
=24.5
residual=actual-predicted
=17.1-24.5=-7.4

Got the same answer for both? feel like I've made a mistake somewhere?


---

"Comment on the improvement or otherwise of each of the transformed equations compared to the original equation (y=6.24+0.993x) . Use mathmatical reasoning to support your comments"

Ok so i found that the orginial equation y=6.24+0.993x had a higher r2 value than the others it was 0.800 and th other transformed questions y2=0.57
logx=0.53
and 1/x=0.26

so based on this the orginal is an imporvment but im not sure on the wording or how to explain this?  Anyone know how i would go about it?

Mod Edit [Aaron]: Merged double post again.

Whats the original question

[Joseph41]

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[BlinkieBill]

Hey guys,
I was wondering whether or not we need to include units when giving residual values?

AND

when we write linear equations do we have to write it in terms of the variables?
as in deseasonalised sales=39 + 23xtime period
or can we just do y=mx+c (if so would we have to first define the variables?)

thanks

[AngelWings]

Hey guys,
I was wondering whether or not we need to include units when giving residual values?

AND

when we write linear equations do we have to write it in terms of the variables?
as in deseasonalised sales=39 + 23xtime period
or can we just do y=mx+c (if so would we have to first define the variables?)

thanks

Q1. Depends on your scenario. I tend not to, unless it's a worded question, but you'd best check with your teacher as I'm about 3 years out of date.
Q2. I like to use the first one that you listed, but I believe either is fine as long as the variables are defined. Again, check with your teacher.

[nicnia]

This is probably a very dumb question!! But finishing my further sac today and later discussing with my friends left me very worried about this lol

Say I obtain a value of 150.3 and need to round it to 3 significant figures. How would I go about that? I ended up rounding it to 151 but many of my friends rounded it to 150 (which is 2 SF's?), and I took my textbook in too which is what I based it off but some of them told me the textbook itself is wrong. Some rounded it to 150.0 but isn't that 4 SF's?... I ended up asking my physics teacher and he said it seemed odd to round it up to 151.

I'm probably overthinking it but would love a clear answer to this!!

[Frosty_Ryan]

Hi,
Could someone help me out with question 11, b (recurrence relations):
Really just need someone to explain how its done... The question is attached below
Thanks a heap xD

[Hungry4Apples]

Hi,
Could someone help me out with question 11, b (recurrence relations):
Really just need someone to explain how its done... The question is attached below
Thanks a heap xD

So it asks for the first seven terms u0 being the first. You simply sub in the previous u value to find the next. I think where you are getting confused is to do with the n-1 part.
All you need to think about is finding the terms, so for u1, you need to sub in u0, since n=1 so n-1=1-1=0
so the first seven terms are, 6, -5 (-6+1), 6 (--5+1), -5, 6, -5, 6
The pattern repeats because it is -u(n+1), so the negative makes a negative a positive
Same technique applies to part 2

[Frosty_Ryan]

So it asks for the first seven terms u0 being the first. You simply sub in the previous u value to find the next. I think where you are getting confused is to do with the n-1 part.
All you need to think about is finding the terms, so for u1, you need to sub in u0, since n=1 so n-1=1-1=0
so the first seven terms are, 6, -5 (-6+1), 6 (--5+1), -5, 6, -5, 6
The pattern repeats because it is -u(n+1), so the negative makes a negative a positive
Same technique applies to part 2

Hi,
 Would you be able to help me with Question 11.B, I understand 11.A completely.
However, no matter what i do it doesn't seem to work out.
Thanks

[AngelWings]

This is probably a very dumb question!! But finishing my further sac today and later discussing with my friends left me very worried about this lol

Say I obtain a value of 150.3 and need to round it to 3 significant figures. How would I go about that? I ended up rounding it to 151 but many of my friends rounded it to 150 (which is 2 SF's?), and I took my textbook in too which is what I based it off but some of them told me the textbook itself is wrong. Some rounded it to 150.0 but isn't that 4 SF's?... I ended up asking my physics teacher and he said it seemed odd to round it up to 151.

I'm probably overthinking it but would love a clear answer to this!!

This is always the tricky part because the 'rules' of significant figures actually vary a little bit between people, let alone in VCE - and this is one that changes between people. I'd say that would normally be 2 significant figures, but some claim 3 for this. If you don't get the mark for it, it's something that can be argued with your teacher and possibly won. They usually do give a little leniency when it comes down to small things like that, with around 1.0 error either side where rounding errors would've occurred. It'll be best if you ask your teacher whether 150 is 3 significant figures or not. (If I were in the same position, I probably would have written 1.50 x 10² to avoid the issue altogether.)

Hi,
 Would you be able to help me with Question 11.B, I understand 11.A completely.
However, no matter what i do it doesn't seem to work out.
Thanks

Have you tried substituting n=2 and using your value for u₁ into the equation? If not, give it a go. The rest may come after you go forwards and backwards with values you know or find out along the way.   

Where can we find the free samples from engage? I cant seem to find them

It's back up and running again, but this time they only have practise exams*. Sorry for that. You can check it out here. Good luck!
If you're keen on getting your hands on a copy of some sample reference pages, I can attach the contents page of mine on to a future post.

* Just realised I've been talking about the wrong company the whole time! It was Connect Education. Due to copyrights, I can't supply it and the website that used to have it has been taken down. I'm terribly sorry to have sent you on a wild goose chase!

[plato]

This is probably a very dumb question!! But finishing my further sac today and later discussing with my friends left me very worried about this lol

Say I obtain a value of 150.3 and need to round it to 3 significant figures. How would I go about that? I ended up rounding it to 151 but many of my friends rounded it to 150 (which is 2 SF's?), and I took my textbook in too which is what I based it off but some of them told me the textbook itself is wrong. Some rounded it to 150.0 but isn't that 4 SF's?... I ended up asking my physics teacher and he said it seemed odd to round it up to 151.

I'm probably overthinking it but would love a clear answer to this!!

150.3 is rounded to three significant figures by writing 150. The zero in this example is the third significant figure.
It is only when you get to have to round 150.5, 150.6, etc will 3 significant figures give 151

[plato]

Hi,
 Would you be able to help me with Question 11.B, I understand 11.A completely.
However, no matter what i do it doesn't seem to work out.
Thanks

The recurrence relation in Question 11 B. has got at least two problems as far as the study design is concerned.
First, and significantly, it is not a first-order recurrence relation and so is not within the scope of the Further curriculum.

U(n+1) is two terms beyond U(n-1) and I thinke there is only enough information given to find U(3), U(5), U(7)  etc. The even-numbered terms within the first seven could only be found if a second "initial" term was given given.

Second, and more trivial, the initial term should be written before the rule, not after it, and should usually be U(0) rather than U(1) but someone may have tried to avoid U(n-1) representing a term called U(-1) as a first term.