Edexcel A2 C4 Mathematics June 2016 - Official Thread

Original post by tiny hobbit

I marked the applied papers upto 1992. There were 7 mechanics questions and one fiendish probability question. You were given the marks of your best 6 answers. If a candidate started with the probability question, you knew that it was because they were rubbish at mechanics and were going to do very badly on the paper.

I've attached one of the papers for your entertainment - it was a bit of a struggle finding one whose filesize was small enough.

Ooh, thank you for that! Were these a "general applied paper" or was it separated in "M1/M2/etc..." - I'm quite liking the look of Q6 and 7 on that paper, I might give them a go. :biggrin:

What's with the lack of statistics, though?

Reply 1182

EnglishMuon

16

Original post by tiny hobbit

The same goes for partial fractions with x^2 + 9 on the bottom, for example. They are specifically ruled out in C4 but will be needed in FP2 or FP3 (I forget which, though probably FP3).

lol I thought it was strange they suddenly disappeared when I was doing past papers last year :tongue:

Do you know why they keep removing little chunks of the syllabus? I mean I always hear people moaning about the course but didnt think that would persuade the exam boards to remove all but the easier stuff.

Reply 1183

Original post by Zacken

Yep! Nah, AFM isn't offered by IAL.

Haha, thanks!

Very impressive.

Can I ask you from a physics graph question quickly, if I have a graph of F against v^2 from the equation - F=mv^2/r. Then how would you be able to gauge the shape of the graph, for constant radius. I would guess at a diagonal line passing through an origin rather than half of a quadratic curve but not too sure.

Based on 3bii 1 from here - http://www.ocr.org.uk/Images/131309-question-paper-unit-g484-the-newtonian-world.pdf

Thanks

Reply 1184

Original post by Mihael_Keehl

Very impressive.

Can I ask you from a physics graph question quickly, if I have a graph of F against v^2 from the equation - F=mv^2/r. Then how would you be able to gauge the shape of the graph, for constant radius. I would guess at a diagonal line passing through an origin rather than half of a quadratic curve but not too sure.

Based on 3bii 1 from here - http://www.ocr.org.uk/Images/131309-question-paper-unit-g484-the-newtonian-world.pdf

Thanks

Yes, it would be a straight line. Write y = F and x = v^2 then your equation is just y = mx for m = m/r. If you were plotting F against v then it would be half a quadratic.

Reply 1185

Glavien

11

Original post by Mihael_Keehl

consider cos(3x-2x) - cos(3x+2x) = cos3xcos2x + sin3xsin2x
- (cos3xcos2x - sin3xsin2x)
= 2sin3xsin2x

eg 2sin3xsin2x = cosx - cos5x

You could do it by parts too.

Hi, how did you know to pick cos(3x-2x) - cos(3x+2x) ?

Reply 1186

tiny hobbit

Original post by Zacken

Ooh, thank you for that! Were these a "general applied paper" or was it separated in "M1/M2/etc..." - I'm quite liking the look of Q6 and 7 on that paper, I might give them a go. :biggrin:

What's with the lack of statistics, though?

This was the syllabus before modules were invented. You did all of your exams at the end of the course, which is what Michael Gove has decided we should return to (he was the previous Education Secretary in the British Government).

There was an alternative syllabus which was Pure and Statistics.

Reply 1187

tiny hobbit

Original post by Zacken

Ooh, thank you for that! Were these a "general applied paper" or was it separated in "M1/M2/etc..." - I'm quite liking the look of Q6 and 7 on that paper, I might give them a go. :biggrin:

What's with the lack of statistics, though?

Original post by EnglishMuon

lol I thought it was strange they suddenly disappeared when I was doing past papers last year :tongue:

Do you know why they keep removing little chunks of the syllabus? I mean I always hear people moaning about the course but didnt think that would persuade the exam boards to remove all but the easier stuff.

Apologies, the Factor formulae seem to have floated on and off the specification a few times. They get a mention in the specification starting in 2000:
"The knowledge and use of identities such as 2 cos A cos B  cos (A + B) + cos (A – B) to solve equations and prove identities"

They seem to have been finally dropped when the current C modules came in in 2004.

Partial fractions with x^2 + 9 were in until 2000 then dropped.

Reply 1188

Original post by Zacken

Yes, it would be a straight line. Write y = F and x = v^2 then your equation is just y = mx for m = m/r. If you were plotting F against v then it would be half a quadratic.

Thank you but is that because m/r is constant, constant gradient implying diagonal line etc.?

Original post by Glavien

Hi, how did you know to pick cos(3x-2x) - cos(3x+2x) ?

Well I knew it would involve factor formulae, and so I saw that sin3xsin2x must cancel out, and we knew what we wanted to get.

Reply 1189

Original post by Mihael_Keehl

Thank you but is that because m/r is constant, constant gradient implying diagonal line etc.?

Yep. We don't call it a diagonal line, by the way - we call it a straight line.

Reply 1190

Original post by Zacken

Yep. We don't call it a diagonal line, by the way - we call it a straight line.

Thank you this makes more sense, and yes haha.

Reply 1191

Original post by Mihael_Keehl

Thank you this makes more sense, and yes haha.

No problem.

Reply 1192

DylanJ42

18

Original post by Zacken

The one on the abnormally easy paper?

Spoiler

nah not that recent

Spoiler

Reply 1193

Original post by DylanJ42

nah not that recent

Spoiler

Oh.

Look at the one I mentioned though, it's even more focused around the technique. :eek:

Reply 1194

DylanJ42

18

Original post by Zacken

Oh.

Look at the one I mentioned though, it's even more focused around the technique. :eek:

oh yea that paper was my most recent mock ,how didnt i remember that question :facepalm:

i was so paranoid during the exam thinking "20 marks for this... :eek:

" I thought i was missing something but apparently not :laugh:

question 1 was a little too straightforward as well (even though i missed it up at the end :tongue:

), easy paper i agree

(edited 8 years ago)

Reply 1195

Original post by DylanJ42

oh yea that paper was my most recent mock ,how didnt i remember that question :facepalm:

i was so paranoid during the exam thinking "20 marks for this... :eek:

" I thought i was missing something but apparently not :laugh:

question 1 was a little too straightforward as well (even though i missed it up at the end :tongue:

), easy paper i agree

Yeah, you know it's easy when it's a 103 for an S. :rofl:

Reply 1196

DylanJ42

18

Original post by Zacken

Yeah, you know it's easy when it's a 103 for an S. :rofl:

i usually have a look at boundaries before I start just to have an idea of how many solutions ill need, so they shocked me a little. But once I started I understood why, I can never usually attempt 6 due to either time constraints/being dumb it was nice to have 6 questions to mark for once. :laugh:

How did you do in it?

Reply 1197

Anon_98

19

Hi Zacken + others. - I hope your Easter holiday is going well.

I was just wondering whether any of you know if we need to learn the Var(x)/E(x) proofs for Uniform distribution- S2? It's just I've seen it being mentioned in a few online resources but then not in others so I'm unsure + don't want to waste memory space/time if it isn't required tbh.

Thanks in advance. :smile:

Reply 1198

Original post by Anon_98

Hi Zacken + others. - I hope your Easter holiday is going well.

I was just wondering whether any of you know if we need to learn the Var(x)/E(x) proofs for Uniform distribution- S2? It's just I've seen it being mentioned in a few online resources but then not in others so I'm unsure + don't want to waste memory space/time if it isn't required tbh.

Thanks in advance. :smile:

Hey! Hope yours is as well. :h:

Bad news: well, I've seen it pop up in a past paper once.

Good news: You don't need to remember it. It's essentially all in your formula book.

Can you see the bit in the "PDF is

\frac{1}{b-a}

" thing? And then above that table is "Expectation/mean is

\int xf(x) \, \mathrm{d}x

" and the corresponding thing for

\text{Var}(x)

?

So all you need to do is, if you're asked to prove it, you don't need to remember anything. Open your formula booklet, they tell you the pdf is

f(x) = \frac{1}{b-a}

, they want you to find the E(X), okay then, just plug it into the formula given:

\displaystyle E(X) = \int xf(x) \, \mathrm{d}x = \int_a^b \frac{x}{b-a} \, \mathrm{d}x = \frac{1}{a-b} \int_a^b x \, \mathrm{d}x

which you can finish up from here.

And they want variance, okay then, still just plugging in:

\displaystyle \text{Var}(X) = \int x^2 f(x) \, \mathrm{d}x - \mu^2 = \int_a^b \frac{x^2}{b-a} \, \mathrm{d}x - \mu^2 = \frac{1}{b-a} \int_a^b x^2 \, \mathrm{d}x - \mu^2

Where

\mu

is just the expectation you found above.

For the expectation:

Spoiler

(edited 8 years ago)

Reply 1199