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# OCR S2- how did it go? watch

1. How did everyone find this?

I thought it was quite hard but some bits were easier than others. Think i have done the plant question wrong as wasnt sure it it was one or 2 tailed test.
2. I thought it was quite easy, only found question 6, the chocolate one, a bit tricky. The plant one i think was two tailed. (if the sig level was 10%, cant remember the question)
3. I thought it was OK actually, I need to an A though so it better have been.
For the plant question I did a one-tailed test, can't remember outcome thought, I think it was to reject the null hypthesis.
What did you get for the min number of coins in Q7, I got 7 but I that question was really dodgy for me.

What am I talking about the plant one was 2-tailed, and my outcome (z statistic) was below -1.645 so I rejected
4. 7 coins sounds about right,
and yeh u reject the plant hypothesis, i think i got -1.819 as the z value.
5. I did 2 tailed and rejected Ho. I think i got 7 for the coin thing too. What did people get for the probability of the type 1 error thing where the probability was 0.8 and 0.6?
6. I thought it was an ok paper- the chocolate question was the worst but I think I did alright. I finished in about 50 minutes which is very early for me in a maths exam. I can't remember my final answer for the last bit about exactly one Ho being rejected for 0.6 and 0.8 but I did a binomial thing with n=2 and p=0.29. I'm terrible at remembering answers!!! x
7. hmm it was ok
i missed out loadsa the last qsts tho - then realised what i had to do right at the end!
i have to get a B overall - i reckon the other maths exams went quite well so just gotta hope now!
What grade does everyone else have to get?
8. (Original post by Nixta)
hmm it was ok
i missed out loadsa the last qsts tho - then realised what i had to do right at the end!
i have to get a B overall - i reckon the other maths exams went quite well so just gotta hope now!
What grade does everyone else have to get?
need an a overall. but a c in this module.
9. that was a hard paper.

The first four questions are usually straihgtforward but not in this exam.

what did people get for the unbiased estimate of variance (2 marks). i didnt do it. What about the second part, what variance figure did u use?
10. I thought it was ok, but I am doing it as part of further maths so it should have been one of the easier papers for me. I only had six coins though....

(Original post by confused?)
that was a hard paper.

The first four questions are usually straihgtforward but not in this exam.

what did people get for the unbiased estimate of variance (2 marks). i didnt do it. What about the second part, what variance figure did u use?
For the unbiased estimate of variance you use (n)/(n-1) multiplied by the variance of the sample. (One of my friends told me that just before the exam - lucky or what!).

You use the estimated figure for variance in the second part. If your estimate was wrong you should still achieve most of the marks through ecf.

.
11. Any idea where we can find past OCR S2 raw -> ums table things, I want to know what the grade boundaries tend to be in terms of raw marks and whether they get scaled up or down when they're converted into UMS. I've trie the OCR website but I can't find anything - I know for AQA I can find it in the examiners' reports but I can't even find any of those on OCR! I need reassurance! (or failing that at least a chance to overanalyse marks...)

Emily
12. (Original post by sebstuart)
I thought it was ok, but I am doing it as part of further maths so it should have been one of the easier papers for me. I only had six coins though....

For the unbiased estimate of variance you use (n)/(n-1) multiplied by the variance of the sample. (One of my friends told me that just before the exam - lucky or what!).

You use the estimated figure for variance in the second part. If your estimate was wrong you should still achieve most of the marks through ecf.

.

i thought the paper was unfair. It also expected us to know how to integrate k/t. I knew how to do it but it shouldnt include this. Also for the unbiased estimate part i use a different layout than what they expected me to use which is why i got it wrong. I need a C to get an overall A, going into the exam i was confident i would at least get that but now im not even sure. I revised well for it aswell. What are peoples opinion on the raw to ums being scaled down or up?
13. it wasnt a particuarly hard paper, so you can assume the 46/60, give or take a few marks will be an a.
14. (Original post by confused?)
i thought the paper was unfair. It also expected us to know how to integrate k/t. I knew how to do it but it shouldnt include this.
From the content specification for 2642: Probability and Statistics 2 (S2) Preamble: "Knowledge of the specification content of modules P1, P2 and S1 is assumed, and candidates may be required to demonstrate such knowledge in answering questions in unit S2."

Integration of 1/x is in P2, hence technically its fine for them to include it. But I agree it maybe was a bit unfair.

(Original post by confused?)
Also for the unbiased estimate part i use a different layout than what they expected me to use which is why i got it wrong.
If a reasonable argument is there you should still get the majority of the marks.

(Original post by confused?)
I need a C to get an overall A, going into the exam i was confident i would at least get that but now im not even sure. I revised well for it aswell. What are peoples opinion on the raw to ums being scaled down or up?
I think the top end (A/B) will not be adjusted much, the middle (B/C) will probably be pushed up a bit (because of the 'hard' marks) and the lower end (D) probably dropped a bit because there seemed to be quite a few 'easy' marks.

I wouldn't worry too much. In January I thought I had got about 60% in M2 because I found it really hard and everyone else said it was easy. In the end I got 92 for that exam. You can never quite be sure how things will turn out.
15. (Original post by emily87)
Any idea where we can find past OCR S2 raw -> ums table things, I want to know what the grade boundaries tend to be in terms of raw marks and whether they get scaled up or down when they're converted into UMS. I've trie the OCR website but I can't find anything - I know for AQA I can find it in the examiners' reports but I can't even find any of those on OCR! I need reassurance! (or failing that at least a chance to overanalyse marks...)

Emily
Well according to my teacher that was the hardest S2 paper she has ever seen! She thinks that low fifties will be equivalent to 100%, so the boundaries should all be shifted down, *crosses fingers*
16. Fingers crossed too, that would be brilliant!!
17. (Original post by moojoo)
Well according to my teacher that was the hardest S2 paper she has ever seen! She thinks that low fifties will be equivalent to 100%, so the boundaries should all be shifted down, *crosses fingers*

seriously, how experienced is your teacher to know this. Hopefully shes right.
18. I don't think your teacher's right. I think it was a fairlr straight forward paper. It was a retake for me. I did it in January, the paper was a lot harder then and Im got 72/100.

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