Stats 2 (S2) OCR (not MEI) 22nd June 2012

Surely question 3 - it was a 1 tail test as it said 'Test at the 5% sig level that the study is correct'.

I know it doesn't affect the overall result (I checked this) but you lose 2 marks for doing it as a 2 tail rather than 1 tail?

No, it's 2-tail. 'Carry out a test of whether the statement "on average one person in three prefers the colour of the object to be blue"' definitely implies 2-tail.

Here are my answers:

1) Random number generator 000 to 999 Agree

2 Var(V)=173 Agree

3) P(X>=7) = 0.0664 larger than 0.025 ACCEPT H0 Agree

4) i) independent Agree
ii) 0.114 Agree
iii) 0.422 Agree
iv) 0.268 Agree

5) 1.1153 < 1.645 ACCEPT H0 Agree

6) i) 0.0449 Agree
ii) 0.0494 Agree

7) ii) a=6 (k=1/72) Agree

iii) Var(X) = 1.35 Agree

8) i) CR >33.1 Agree
ii) Type I error Agree
iii) 0.0159 , mean not 30 because probability so small Agree
iv) mean is 33.58 Agree

Any thoughts guys?

Agree with everything that's been said, but the
8iii) Hench state whether you think that mu = 30, giving a reason.

I got the probability that Ho is rejected etc..to be like 0.00159 or whatever
I then said that as the Type I Error was so small, then mu IS =30, as every hypothesis test has a Type I Error.

If that makes sense.

I don't think I put 8iv) to 4 sig fig x_x

Well this looks just spectacular I'm very happy that our answers match

For the blue colour hypothesis test?

Is this answer equally valid for all 7 marks?

I found the critical region by testing values above and below until the probability of it being at least that value or more was less than 0.025 (half the significance level)

I got the rejection region as X=0 and X≥8 (can someone check whether that is correct for B(12, 1/3)) and said that since 7 < 8 then ACCEPT the null hypothesis.

anyone got the paper or list of the questions?

Question 3 -

Couldn't it be modelled by a poisson since we are given a rate at which people prefer the blue room ( 1 in 3) therefore if we are now told the sample size is 12 couldn't we use a poisson with parameter 4?

Don't see why this couldn't work - could there be 2 solutions?


Grade boundaries are looking like they could be 71 for a B!!!

Hello! For all who took this paper and don't already know that the boundaries are out, they are as follows:

Max Raw mark: 72
90 UMS (a*): 66
80 UMS (A): 60
70 UMS (B): 53
60 UMS (C): 46
50 UMS (D): 39
40 UMS (E): 32

Source