You are Here: Home >< Maths

# Edexcel S2 - 27th June 2016 AM Watch

• View Poll Results: How did you find the Edexcel S2 exam?
Very hard
145
14.71%
Hard
331
33.57%
Normal
293
29.72%
Easy
152
15.42%
Very easy
65
6.59%

1. (Original post by AJC1997)
grade boundary predictions? I got somewhere between 62-70 and need 80UMS in this exam
it will drop down this year - I would say 62 maybe even 60 for an A as this was SO much harder than the 2015 paper
2. (Original post by fefssdf)
thats exactly what I did !
The expected value of A = the expected value of Pi * R^2.

So it's Pi * E(R^2) rather than Pi times (E(R))^2.
3. (Original post by iipebblesii)
I got this too
Essentially A is not modelled by a continuous uniform distribution so you can't use it. Instead you need to use the formula in the formula book
4. (Original post by iipebblesii)
I got this too

HOW TO FIND E(A)

Posted from TSR Mobile
5. (Original post by hwilkoo)
Can someone please explain E(A), as i got it to equal 49pi.

E(R) = (9+5)/2
E(R) = 7

E(A) = pi * 7^2
E(A) = 49pi
A = pi*R^2
E(A) = E(pi*R^2)
E(A) = pi*E(R^2)

so you had to work out Var(R) ( I think it was 4/3 or something?), and E(R) (7), and then use Var(R) = E(R^2) - E(R)^2, so E(R^2) = Var(R) + E(R)^2 = 4/3 + 49 = 151/3. So E(A) = piE(R^2) = 151pi/3 = 158.1.
6. (Original post by fefssdf)
it will drop down this year - I would say 62 maybe even 60 for an A as this was SO much harder than the 2015 paper
No way, this was easier than most simple because there were 2 long 'prove that' questions so people will get those. It'll be standard boundaries at the least

Posted from TSR Mobile
7. (Original post by Mattematics)
The expected value of A = the expected value of Pi * R^2.

So it's Pi * E(R^2) rather than Pi times (E(R))^2.
Thought that could be the case! Thanks
8. (Original post by Supermanxxxxxx)
For the 8 marker I got n=87 but I think I messed up when hiding the quadratic how many marks do you think Tisi Weill be

Posted from TSR Mobile
i messed this up as well - I got like n=62 lol - you should get like 5/8 if you got up to making a quadratic tbh
9. That was horrible!
10. (Original post by iMacJack)

HOW TO FIND E(A)

Posted from TSR Mobile
i did it by integration but fair enough
11. (Original post by M3WIZARD)
Question 1a) U = 1.44 Var(x) = 1.44 (3 Marks)b) U was approximately Variance (1 Mark)c) I – 0.251 II – 0.777 (4 Marks)d) 0.1378 (3 Marks)e) 0.152 (3 Marks) (Might be 0.132 – Rushed this onmy copy of answers) Question 2a) N=60 (2 Marks)b) I – 0.0133 II -0.0159 (5 Marks)c) 0.2396>0.01 Keep H0 (5 Marks)Question 3a) f(x) = ¼ 5=<R=<9 , 0 otherwise (1 Marks)b) 0.5 (1 Marks)c) 158.13 (4 Marks)Question 4a) Show that (6 Marks)b) K = 1/9 (4 Marks)Question 5 N = 225(I applied continuity correction – I honestly didn’t know if I should) (8Marks)Question 6a) 9 samples (2 Marks)b) 4 = ¼ , 5 = 3/10 , 6= 29/100 , 7 = 3/25, 8 =1/25 (5 Marks)c) N=57 (3 Marks)Question 7a) 1.2 (4 Marks)b) 0.24 (4 Marks)c) 0.325 (3 Marks)d) £41.88 (2 Marks)e) Shouldn’t remove staples (2 Marks) I’m not claiming these are all right – let me know J These are what I wrote
Got the same except the mean for the first one was 1.41.

Posted from TSR Mobile
12. (Original post by Nikhilm)
No way, this was easier than most simple because there were 2 long 'prove that' questions so people will get those. It'll be standard boundaries at the least

Posted from TSR Mobile
really... well are you suggesting it will be higher than 67 for an A cause that seems very unlikely...
13. Went alright but was nothing like the past papers. Got stuck on finding k for 20 minutes and decided to move on, how did you guys do it? I got k = 1/(a+21) and couldnt hew another equation in a from it
14. (Original post by hwilkoo)
Can someone please explain E(A), as i got it to equal 49pi.

E(R) = (9+5)/2
E(R) = 7

E(A) = pi * 7^2
E(A) = 49pi
Same here..?
15. (Original post by iMacJack)

HOW TO FIND E(A)

Posted from TSR Mobile
(Original post by ThatPerson2)
A = pi*R^2
E(A) = E(pi*R^2)
E(A) = pi*E(R^2)

so you had to work out Var(R) ( I think it was 4/3 or something?), and E(R) (7), and then use Var(R) = E(R^2) - E(R)^2, so E(R^2) = Var(R) + E(R)^2 = 4/3 + 49 = 151/3. So E(A) = piE(R^2) = 151pi/3 = 158.1.

Thanks guys, i get it now
16. (Original post by exclamationmark)
How many marks was it to find the sample distribution of the other means?
I think 5 marks
17. I thought it was an ok paper and I didn't revise anything until half an hour before the exam and I'd like to think I got a safe B but I feel screwed for D2 tomorrow
18. (Original post by fefssdf)
really... well are you suggesting it will be higher than 67 for an A cause that seems very unlikely...
I sat S2 last year as well (got 69/75) and i'd have to say the grade boundaries would be about 67 for an A
19. How did I find this harder than fp2
20. [5,9]
I did 5^2pi = 25pi and 9^2pi = 81pi
Then i wrote [25pi,81pi]
E(X) = 1/2(25pi+81pi)
= 53pi

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: August 20, 2016
Today on TSR

### Medicine offers rolling in

Which unis have sent theirs?

### I refused to be served by tattooed cashier

Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll
Useful resources

Can you help? Study help unanswered threadsStudy Help rules and posting guidelinesLaTex guide for writing equations on TSR

## Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.