VCE Methods Question Thread!

[itsdanny]

You wouldn't have to be as rigorous as that in methods. Not that using limit notation is that rigorous, but that's sort of the point I guess - simply slapping the limit sign in front of it doesn't really change what you're doing. Whether you use limit notation or abbreviate it with terminals, either can be done without really knowing what a limit is. So it would be pretty stupid of VCAA to prefer one over the other.

I don't think VCAA has actually ever required limit notation in any of their answers. Take for example question 2b from 2011 exam 2 (in particular the solutions in the assessment report). This is the only instance where it might have been appropriate (that I can remember), but they use the abbreviated from.

Ok well thanks for the help guys.

[Damoz.G]

I did the 2012 VCAA exam 1 yesterday... Got 38/40 (fuckin conditional probability)

Did the 2012 VCAA exam 2 before... I got 59/80... -_-


I feel like shit now, I've been studying and doing heaps of practice exams and I just fucked up the actual exam from last year.
This was a VCAA exam as well , not a commercial one.
If I had been part of the 2012 cohort last year sitting the exam I would've actually started crying after they said pens down.

Holy shit I am feeling down at the moment lol

Don't worry. Quite a few people in my School have felt the same after they had done it recently. I haven't gone through the pain of doing it.....yet. :p

I'll probably do it next weekend.

[Phy124]

I did the 2012 VCAA exam 1 yesterday... Got 38/40 (fuckin conditional probability)

Did the 2012 VCAA exam 2 before... I got 59/80... -_-


I feel like shit now, I've been studying and doing heaps of practice exams and I just fucked up the actual exam from last year.
This was a VCAA exam as well , not a commercial one.
If I had been part of the 2012 cohort last year sitting the exam I would've actually started crying after they said pens down.

Holy shit I am feeling down at the moment lol

Firstly, 59/80 on last years exam would have been a high A (marginally below A+ cutoff) so it's not as bad as you may think.

Secondly, one bad (italics due to being subjective) result isn't a true indicator of where you are at with your knowledge of the material.

Now, what do you feel the reason for obtaining a score lower than you wanted was? Did you just have a bad day? Or is it because you have gaps in your knowledge? Or possibly because you aren't able to interpret examination 2 questions?

If it's the latter and other exam 2 results have been similar, then maybe you need to focus more on extended response (or MC questions, if you lost out there). A lot of students seem to neglect exam 2's during practice as they can smash out a heap of exam 1's in a short period of time, while finding exam 2's considerably longer and more arduous. If this is the case I would like to point out that it is important to fine tune your ability across all areas. It's all well and good if you have a solid grasp of the concepts, however, if you can't apply them because you can't interpret the question, then you'll be in a lot of trouble.

Finally, we all have bad days where we struggle with questions we can usually do. So, if this was the case, I wouldn't worry too much. Lift your head, take a break and then get straight back into it

[lzxnl]

The A+ cutoff for exam 2 was, from memory, 64/80; 59 isn't marginally below that.

[Phy124]

The A+ cutoff for exam 2 was, from memory, 64/80; 59 isn't marginally below that.

It was 61.5, while The A cutoff was 51.5. Therefore I don't think it is wrong to describe 59 as being a high A and marginally below the A+ cutoff, considering the exam was out of 80 I was merely trying to increase BasicAcid's confidence.

[Smiley_]

Firstly, 59/80 on last years exam would have been a high A (marginally below A+ cutoff) so it's not as bad as you may think.

Secondly, one bad (italics due to being subjective) result isn't a true indicator of where you are at with your knowledge of the material.

Now, what do you feel the reason for obtaining a score lower than you wanted was? Did you just have a bad day? Or is it because you have gaps in your knowledge? Or possibly because you aren't able to interpret examination 2 questions?

If it's the latter and other exam 2 results have been similar, then maybe you need to focus more on extended response (or MC questions, if you lost out there). A lot of students seem to neglect exam 2's during practice as they can smash out a heap of exam 1's in a short period of time, while finding exam 2's considerably longer and more arduous. If this is the case I would like to point out that it is important to fine tune your ability across all areas. It's all well and good if you have a solid grasp of the concepts, however, if you can't apply them because you can't interpret the question, then you'll be in a lot of trouble.

Finally, we all have bad days where we struggle with questions we can usually do. So, if this was the case, I wouldn't worry too much. Lift your head, take a break and then get straight back into it

i got way less than that sooo

[lzxnl]

It was 61.5, while The A cutoff was 51.5. Therefore I don't think it is wrong to describe 59 as being a high A and marginally below the A+ cutoff, considering the exam was out of 80 I was merely trying to increase BasicAcid's confidence.

Yeah ok I just checked and I probably just memorised the wrong year's cutoffs

[gibbsy06]

Hey I'm struggling with this question (Q7 Heffernan 2011 Exam 1)

A spherical balloon is being inflated. Its volume is increasing at a rate of 2cm^3 per second. Find the rate in cm/sec, at which the radius of the balloon is increasing when the radius is 4cm.

I know that this is a related rates question, and that dV/dt = 2[cm^3], and that I'm looking for dr/dt using the chain rule. But how am I supposed to get it?

Cheers.

(Note: can someone chuck this in that sweet looking maths code? I'm on my phone typing this out. Cheers)

[Stevensmay]

for a sphere.
And from the question.

As you say, we want to find
We can treat these as fractions so

To find we differentiate the volume of a sphere

But wait, we have not

This is easy to fix, we divide 1 by .


We now multiply our two derivatives together to get


Substitute in our value for r, 4.


And finished!

[b^3]

HINT:

HINT2

EDIT: Beaten, 32 seconds

[gibbsy06]

Just did the question using your reasoning and while I understand it and it worked, what allows us to treat the derivatives as fractions? Sorry if I sound a bit slow (I know we covered it a while back), but yeah, I'm not quite sure how that is allowed?

[Damoz.G]

Just did the question using your reasoning and while I understand it and it worked, what allows us to treat the derivatives as fractions? Sorry if I sound a bit slow (I know we covered it a while back), but yeah, I'm not quite sure how that is allowed?

You use fractions to cancel what you don't need, but still use the other information to get to your answer. In that example, we only wanted dr/dt, but we still needed more information to get to the final answer. So by simply cancelling the fractions allows us to get to the "fraction" or answer that we want.

It's a bit hard to explain on here.

[b^3]

Derivatives aren't fractions, but we can sometimes 'treat' single derivatives as fractions, (you're not really dealing with fractions).

What we're actually doing is applying the chain rule. We have as a function of (rearrange for in terms of , while you don't actually do this in the problem, it works for the explanation, and you effectively bring it back when you flip it, if you were to substitute the other back into it), i.e. , and we have as a function of , .

So if we were to differentiate with respect to , we need to apply the intermediate step in the middle and apply the chain rule by 'multiplying by the derivative of the inside'

[ahat]

Just did the question using your reasoning and while I understand it and it worked, what allows us to treat the derivatives as fractions? Sorry if I sound a bit slow (I know we covered it a while back), but yeah, I'm not quite sure how that is allowed?

Also, a calculus question on the exams is nearly always going to give you three different variables. One that you are trying to find (for example, ) and then it will give you a clue for what the other two may be. If it's a shape, say a cone, we can find the volume and then find the derivative , which we would flip when we put it into the equation. So this is the rate you have to figure out. The other rate will be given in the question, such as change in volume with time, i.e. dv/dt) and then you can connect allll of these using the chain rule.

       
As the other guys have said, even though these aren't fractions but rather rates  (how an independent variable changes according to an dependent variable - if that makes sense and I got it the right way ) we can still use the chain rule and shadily treat them as fraction, cancelling those (?)'s out.

btw, for the example I've given, ? is going to be

[Sanguinne]

vcaa 06 1d extended response

Let h:R --> R, h(x) = 2|sin(x)|. Find the general solution, for x, of the equation h(x) = 1.