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    (Original post by sam_97)
    How did everyone find the exam overall? Similar difficulty to last year?
    I think it was a fair bit easier than last year's - I think A* will be around 68-69
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    (Original post by sam_97)
    I got 0.622 as well
    (Original post by tanyapotter)
    I got 0.622 :/
    I did (1-P(X<=0)(1-P(X<=0)(1-P(X<=0) for all 3 and multiplied it, was that the right method?

    I may have just inputted a value incorrectly
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    (Original post by sam_97)
    I think that is the value I got, although I rounded it to 2.34
    Yup

    What did you put for the comment?
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    This is the kind of exam where the answers are random decimals and I really really really can't remember any of it. I remember some if people say it but everything's a Blurr after I walk out.

    I feel like I've lost a couple on "comment" questions but it was an okay paper I think. I preferred it to last years. Any predictions for A* boundaries?
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    (Original post by Suits101)
    I did (1-P(X<=0)(1-P(X<=0)(1-P(X<=0) for all 3 and multiplied it, was that the right method?

    I may have just inputted a value incorrectly
    That is the method I used as well. Even if your final answer is incorrect, you will have picked up method marks for definite.
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    (Original post by Suits101)
    I did (1-P(X<=0)(1-P(X<=0)(1-P(X<=0) for all 3 and multiplied it, was that the right method?

    I may have just inputted a value incorrectly
    P(X<=0) is the same as P(X=0) - maybe that's where you went wrong?
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    Hey guys! I had time at the end of the exam so I wrote down most (not all) of the answers I put on my calculator. Obviously some will likely be wrong but here's what I put so we can compare:
    1) 0.703, 0.870, 0.133, 0.144, 0.622
    2) mean=31.7 sd^2=2024.4
    3) 0.35, 0.315, 2.77, 31p, £2.77
    4) 0.7, sd(x)=0.0289
    5) Z=2.34
    6) (can't remember what I put for crit value of island A lizards), Mu(B)=15.1cm
    7) For graph I had straight horizontal line from (1, 1/4) to (4, 1/4) and then straight line going down to (6,0) and 0 otherwise.
    E(X)=3.04
    Let me know if you think any are wrong (i think 1b might be). Thanks!
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    (Original post by tanyapotter)
    P(X<=0) is the same as P(X=0) - maybe that's where you went wrong?
    It's the same thing - damn must've inputted it wrong!

    (Original post by sam_97)
    That is the method I used as well. Even if your final answer is incorrect, you will have picked up method marks for definite.
    Thanks

    I'm just glad that I should be able to get one mark on that question as I had no idea!
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    (Original post by Suits101)
    Yup

    What did you put for the comment?
    I failed to reject Ho, as 2.34 lies outside the critical region. Then I made some comment in context about there being no association between the type of engine and car problems.
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    (Original post by Suits101)
    I did that but accepted H0.

    You can't accept or reject H1, only accept or reject H0.
    Yeah that's what I wrote so it's all good
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    (Original post by df97)
    Hey guys! I had time at the end of the exam so I wrote down most (not all) of the answers I put on my calculator. Obviously some will likely be wrong but here's what I put so we can compare:
    1) 0.703, 0.870, 0.133, 0.144, 0.622
    2) mean=31.7 sd^2=2024.4
    3) 0.35, 0.315, 2.77, 31p, £2.77
    4) 0.7, sd(x)=0.0289
    5) Z=2.34
    6) (can't remember what I put for crit value of island A lizards), Mu(B)=15.1cm
    7) For graph I had straight horizontal line from (1, 1/4) to (4, 1/4) and then straight line going down to (6,0) and 0 otherwise.
    E(X)=3.04
    Let me know if you think any are wrong (i think 1b might be). Thanks!
    Hi!

    I agree with all but 1(b) I got 0.669
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    (Original post by Suits101)
    This is what I remember and it MAY NOT BE RIGHT

    1(a) 0,7029
    1(b) 0.669
    1(c) 0.1327
    1(d) 0.144
    1(e) 0.462 (should be 0.622?)

    2. Mean = ? s2 = ?

    3(a) 0.350
    3(b) 0.1575
    3(c) Var(x) = 2.7736
    3(d) Poisson cannot have an upper limit, people don't borrow books at a constant average rate
    3(e)(i) 30.8p
    3(e)(ii) 5.27p

    4
    (a) k = 10
    (b) P = 0.70
    (c) E(X) = 0.05
    (d) Integrate, ans = 1/300
    (e) SD(X) = 0.0289

    5(a) Test statistic = 2.3386, CV = 2.706 so accept null
    5(b) comment

    7(a) Draw graph - DENSITY function, so have to differentiate
    7(b) 61/6 but I got it wrong
    1e was 0.622

    3b, you had to do 0.35x0.45x2, as there were 2 combinations
    3d. 1st I agree, 2nd point I said P(X=x)=0, which implies e^(-lambda)=0 which is nonsense
    2eii. asked fro variance, not sd
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    (Original post by Krithika256)
    Any predictions for grade boundaries?
    65-A 70-A*, more or less the same as 2014 and 1025, maybe closer to the lower of the two
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    (Original post by MahuduElec)
    1e was 0.622

    3b, you had to do 0.35x0.45x2, as there were 2 combinations
    3d. 1st I agree, 2nd point I said P(X=x)=0, which implies e^(-lambda)=0 which is nonsense
    2eii. asked fro variance, not sd
    I was going to do that for 3(b) - damn!

    3(e)(ii) - are you sure? Damn!
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    (Original post by Salty carpet)
    Same. Anyone remember their chi^2 value or how they found it? I merged the first two columns and then used Yate's correction... can't remember my value, although I did reject H1
    2.3ish and accepted H0, so reject H1 yes (although you should put acceot H0)
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    0.703
    0.669
    0.133
    0.144
    0.622

    mean - 31.7 o^2 - can't remember

    0.35
    0.158
    2.77
    30.8
    16.7
    10
    0.7
    0.05
    1/300
    root3 / 60
    14.9
    18.5


    ANSWER DUMP. didn't do the last 4 marker.
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    I think I said there was association between the engine and mechanical problems, meaning it would be tough to still get the 2 marks for the comment after. I think I mentioned that one of the expected values for Diesel was considerably lower than the actual value and tried to use this to suggest why there was association. I used all the correct terms and stuff, do you think I would still get 2 marks for the comment?
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    (Original post by sam_97)
    How did everyone find the exam overall? Similar difficulty to last year?
    About the same yes, the last Q in both had sneaky tricks
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    (Original post by tanyapotter)
    I think it was a fair bit easier than last year's - I think A* will be around 68-69
    Agreed. I don't think the grade boundaries will change much compared to last year to be honest, 70+ will definitely be an A*.

    (Original post by KB_97)
    This is the kind of exam where the answers are random decimals and I really really really can't remember any of it. I remember some if people say it but everything's a Blurr after I walk out.

    I feel like I've lost a couple on "comment" questions but it was an okay paper I think. I preferred it to last years. Any predictions for A* boundaries?
    Sometimes they can be really picky with the explain questions so it's easy to drop a couple of marks here and there, even if you think your answer is correct.

    I think the boundary for A* will be somewhere between 67-69, but it is always difficult to tell. Best to wait until the day before results day to find out
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    (Original post by Suits101)
    Hi!

    I agree with all but 1(b) I got 0.669 and 3(b) I got 0.1575 (0.35 x 0.45 - may be wrong) and 3(e)(ii) I got 5.27p (may be wrong)
    For 3(b) I did 2(0.35 x 0.45) as there are two possible ways of people taking out the books (either first guy got out more than 3 and second got out less than 3 or vice versa). Not sure if I'm right but either way we have very similar answers which is good news!
    For 3(e)(ii) I did 2.77 x 10^2 as var(aX)=a^2var(X), likewise I'm unsure on this one too.
 
 
 
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