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Thread: Can someone please explain how to compute the mean and standard deviation for this qu

  1. November 19th 2009, 06:13 AM #1
    Ttops
    Ttops is offline
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    Question Can someone please explain how to compute the mean and standard deviation for this qu

    I wasnt sure where to post this question but since it`s stats, i decided to post it here.

    p(x)=(1/4)(3/4)^(x-1), X=1,2,3,4

    I'm totally confused on how to do it...the question and answer is in the word.doc provided but i need an explanation on how the answer is created.
    Thank you.
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  2. November 19th 2009, 09:04 PM #2
    qmech
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    calculating mean and std dev

    The mean (mu) is calculated by:
    <br /> \mu = 1 * p(1) + 2 * p(2) + 3 * p(3) + ....<br />
    The standard deviation obeys a rule saying
    <br /> \sigma ^ 2 = E(X^2) - (E(X)) ^ 2<br />
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