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Math Help - Statistics

  1. #1
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    Statistics

    I need help with this question please.
    The random variable X is given by the sum of the scores when two ordinary dice are thrown.
    i) i need to use the shape of the distribution to find E(X)=U
    ( but i dont know what i need to draw for that...)
    From this i should also be able to valculate Var(X)=0^2


    Finally i need to find P(X<U) and P(X>U+o) < could someone please tell what these mean and how to calculate .

    Thank you
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by Chez_ View Post
    I need help with this question please.
    The random variable X is given by the sum of the scores when two ordinary dice are thrown.
    i) i need to use the shape of the distribution to find E(X)=U
    ( but i dont know what i need to draw for that...)
    From this i should also be able to valculate Var(X)=0^2


    Finally i need to find P(X<U) and P(X>U+o) < could someone please tell what these mean and how to calculate .

    Thank you
    You need to calculate the probability of the outcomes X=2, 3, ..., 12 by
    counting how many of the 36 possible outcomes (when the dice are
    distinguishable) give each score and then dividing by 36:

    P(X=2)=1/36
    P(X=3)=2/36
    P(X=4)=3/26
    P(X=5)=4/36
    :
    :
    P(X=12)=1/36

    Once you have these probabilities your notes will tell you how to compute the
    expectation and varianve etc.

    RonL
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