2008 April Exam

Discussion in 'CT3' started by ALEX_AK, Apr 10, 2008.

  1. ALEX_AK

    ALEX_AK Member

    Hello,

    I know there will be examiners report for every papers. However I am dying to know how to solve the question on 100 fences.

    I think its very simple but I am afraid that I could have misinterpreted the question.
     
  2. spjgriw

    spjgriw Member



    For me the maximum likelihood question was the horror of the exam!
     
    Last edited by a moderator: Apr 10, 2008
  3. spjgriw

    spjgriw Member

    Overall I have to say I didn't find that a very pleasant experience! What's the pass mark on CT3?
     
  4. Inglis Drever

    Inglis Drever Member

    tough enough exam but thought it was fair, nothing really that wasnt in the notes. struggled for time though which was a surprise, all the past papers i did with time to spare. hard to know what the pass mark will be but i'd imagine it will be around 63/64??

    ps. tiger at 2s now on betfair, get on!
     
  5. Michael

    Michael Member

    Yup, tough-ish but fair sounds about right. I had trouble with a few questions that seemed a little unusual compared to older exams, but think I managed to figure them all out okay in the end. I realised with minutes to spare that I hadn't proven one of my MLEs was actually a maximum, so had some frantic last-minute calculus to do :eek:

    Alex - for the fencepost question I just applied the central limit theorem, to get something like:
    Sum of the Xi's ~ N(0, 100*3^2)
    but I wasn't entirely convinced that I hadn't missed the point.
     
  6. Jonny

    Jonny Member

    I too thought the exam was fair but struggled for time. Which is annoying as sitting the past papers before the actual exam, i did not have this time problem. It Just proves you cant actually sit these past papers under real exam conditions. Because you just dont feel the pressure!!!! Is this thought echoed by others, did you feel the pressurised by the time?
     
  7. Jonny

    Jonny Member

    Michael,

    I applied the central limit theorem for the fence question like you did at the last minute. But it was quite possible that i may have mis interpretted the question.

    As for the likelihood question, how did you guys evaluate \lambda using the Binomial K?
     
  8. spjgriw

    spjgriw Member

    Yes the time factor was the biggest problem, it left me with about 10 minutes to do the maximum likelihood question that I'd left until last. Which I might add was not enough! For the wood cutting thing I used the central limit theorem too, you end up with N(0, 100*var)
     
  9. Michael

    Michael Member

    It took me the whole 3 hours, but I didn't feel too pressured by the time - I did all the easier questions first which let me take my time with the trickier ones. I usually find it easier to focus in the real exams though, my mind doesn't wander quite so much.

    Jonny, for the MLE question with K ~ Bin(n, p), where p was some exponential function of theta, I think I took
    L(theta) = (1 - p)^k * p^(n-k)
    and went through the standard procedure to find theta-hat. But again I wasn't sure that I was interpreting the question correctly.
     

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