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# S2 ocr mei 31st may statistics 2

Maths exam discussion - share revision tips in preparation for GCSE, A Level and other maths exams and discuss how they went afterwards.

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1. Re: S2 ocr mei 31st may statistics 2
Lol I got 211 for k, FML
2. Re: S2 ocr mei 31st may statistics 2
(Original post by Fatima0065)
Did you guys do (np,npq) and get 78.93...or sumthing liek that for the aprriximating question?
yes i got X-No(80, 79.93) i think
3. Re: S2 ocr mei 31st may statistics 2
(Original post by sumsum123)
Hey, what did you get for k?
I've completely forgot haha. i know i found Z using the inverse of (1-0.05), or whatever the % was.
4. Re: S2 ocr mei 31st may statistics 2
(Original post by rainbowsxyz)
yes i got X-No(80, 79.93) i think
Yes! thanks!
5. Re: S2 ocr mei 31st may statistics 2
I'm so glad we didn't have a wordy chi squared question too! Woohoo
6. Re: S2 ocr mei 31st may statistics 2
(Original post by Fatima0065)
Yes! thanks!
haha no worries, reassuring to know I'm not the only one =D
7. Re: S2 ocr mei 31st may statistics 2
(Original post by rainbowsxyz)
yes i got X-No(80, 79.93) i think
Thank you so much.
8. Re: S2 ocr mei 31st may statistics 2
For the hypothesis testing questionS, did anyone get all the results as being significant. i.e reject H0.?
And then for the first on where it asks if your conclusion would change if you used 1%, you say yes, the result would be insignificant. i.e Cannot reject H0?
9. Re: S2 ocr mei 31st may statistics 2
Did everyone get for the 3 hypothesis testing, accept H1?
10. Re: S2 ocr mei 31st may statistics 2
(Original post by steven hawking)
For the hypothesis testing questionS, did anyone get all the results as being significant. i.e reject H0.?
And then for the first on where it asks if your conclusion would change if you used 1%, you say yes, the result would be insignificant. i.e Cannot reject H0?
I had a mixture of rejecting and accepting in the paper, i know in the chi squared i found it was significant.
11. Re: S2 ocr mei 31st may statistics 2
I used X~N(80,80) because the first part led you to Poisson? Also I used a negative Z value because it was the lower end of the distribution...

((k+0.5)-80)/rt80 > -1.645

And rearranged to give k>64.79... Hence k=65

Did anyone else do something similar?
12. Re: S2 ocr mei 31st may statistics 2
i got significant for all 3. I didnt use X-N(np,npq) at all??
13. Re: S2 ocr mei 31st may statistics 2
(Original post by Milanx)
Did everyone get for the 3 hypothesis testing, accept H1?
I did.
Then for the one where they asked if you used 1% instead, the conclusion changes to Accept H0 (insignificant)
14. Re: S2 ocr mei 31st may statistics 2
(Original post by AlexBamsey)
I had a mixture of rejecting and accepting in the paper, i know in the chi squared i found it was significant.
The chi square test statistic was 12.68,
the critical value was 13.28
So chi-square<critical value, RESULT NOT SIGNIFICANT.
15. Re: S2 ocr mei 31st may statistics 2
but u take the absolute value remember
16. Re: S2 ocr mei 31st may statistics 2
(Original post by shanban)
I used X~N(80,80) because the first part led you to Poisson? Also I used a negative Z value because it was the lower end of the distribution...

((k+0.5)-80)/rt80 > -1.645

And rearranged to give k>64.79... Hence k=65

Did anyone else do something similar?
I cant be 100% sure, but your final answer sounds similar to what i got.
Besides i think the most common mistake in that question will be to forget the continuity correction, which you remembered
17. Re: S2 ocr mei 31st may statistics 2
(Original post by albus)
The chi square test statistic was 12.68,
the critical value was 13.28
So chi-square<critical value, RESULT NOT SIGNIFICANT.
That's the critical vaue for 4 degrees of freedom and, correct me if I'm wrong, there were (4-1)(2-1)=3 degrees of freedom hence the critical value was 11.34 so the result is significant.
18. Re: S2 ocr mei 31st may statistics 2
would you still get follow throught marks even if you put the wrong variance for q2?
19. Re: S2 ocr mei 31st may statistics 2
(Original post by shanban)
I used X~N(80,80) because the first part led you to Poisson? Also I used a negative Z value because it was the lower end of the distribution...

((k+0.5)-80)/rt80 > -1.645

And rearranged to give k>64.79... Hence k=65

Did anyone else do something similar?
Yeah but I used 80,79.73(or something like that) and accidently used variance rather than SD for the sigma, would I only lose one mark for this?
20. Re: S2 ocr mei 31st may statistics 2
(Original post by albus)
The chi square test statistic was 12.68,
the critical value was 13.28
So chi-square<critical value, RESULT NOT SIGNIFICANT.
critical value was 11.34 or something. because degrees of freedom was 3 not 4

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