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    "I have a die with six faces numbered consecutively from 1 to 6. What is odd about it is that the probability of rolling the face with the number k is c*q^k, where c is a constant and q=0.96 What is the expected value of the roll of the dice"

    I'm abit puzzled why I'm getting a wrong answer. The answer is 3.3811 according to mark scheme.
    Don't you just integrate k*c*q^k between 1 to 6. As for c I got 0.191798..
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    (Original post by Mentally)
    "I have a die with six faces numbered consecutively from 1 to 6. What is odd about it is that the probability of rolling the face with the number k is c*q^k, where c is a constant and q=0.96 What is the expected value of the roll of the dice"

    I'm abit puzzled why I'm getting a wrong answer. The answer is 3.3811 according to mark scheme.
    Don't you just integrate k*c*q^k between 1 to 6. As for c I got 0.191798..
    Yikes.. integrating kcq^k wrt k sounds like a nasty business, how did you do it?
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    (Original post by Mentally)
    "I have a die with six faces numbered consecutively from 1 to 6. What is odd about it is that the probability of rolling the face with the number k is c*q^k, where c is a constant and q=0.96 What is the expected value of the roll of the dice"

    I'm abit puzzled why I'm getting a wrong answer. The answer is 3.3811 according to mark scheme.
    Don't you just integrate k*c*q^k between 1 to 6. As for c I got 0.191798..
    I've not completed this question myself, but the distribution is discrete, not continuous, so your integration should be a summation.

    (Original post by SeanFM)
    Yikes.. integrating kcq^k wrt k sounds like a nasty business, how did you do it?
    For interest's sake, in this case you would write q^k=e^{k\ln(q)} and proceed from there.
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    (Original post by joostan)
    I've not completed this question myself, but the distribution is discrete, not continuous, so your integration should be a summation.



    For interest's sake, in this case you would write q^k=e^{k\ln(q)} and proceed from there.
    Ah, I see. Not something you come across at A-level though I was thinking of using the definition of integration in the discrete case too, and it should get them the right answer. .
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    (Original post by SeanFM)
    Yikes.. integrating kcq^k wrt k sounds like a nasty business, how did you do it?
    I used Joostan method

    (Original post by joostan)
    I've not completed this question myself, but the distribution is discrete, not continuous, so your integration should be a summation.
    *facepalm* ofcourse, I need to stop making these dumb mistakes lol


    (Original post by SeanFM)
    Ah, I see. Not something you come across at A-level though I was thinking of using the definition of integration in the discrete case too, and it should get them the right answer. .
    Its my Uni-work, but it resembles some content that some able S2 students should be able to do so I posted anyway
    Thanks so much for the help guys!
 
 
 
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