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Math Help - Standard deviation of a random variable

  1. #1
    Junior Member
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    Standard deviation of a random variable

    I believe the answer given is wrong for the following question:

    Determine the mean and standard deviation of the random variable whose probability distribution is
    x = 2, P(x) = .1
    x = 4, P(x) = .2
    x = 6, P(x) = .4
    x = 8, P(x) = .2
    x = 10, P(x) = .1
    My answer is \mu = 6, \sigma \approx 2.28. The book says that \sigma = 2.19. Who's right?
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by earachefl View Post
    I believe the answer given is wrong for the following question:



    My answer is \mu = 6, \sigma \approx 2.28. The book says that \sigma = 2.19. Who's right?
    The book (assuming you have \mu right).

    RonL
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  3. #3
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    argghhh.... stupid math error....
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