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Math Help - Mean, Variance, and Standard Deviation

  1. #1
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    Mean, Variance, and Standard Deviation

    x ------ 1 ------- 2 -------3-------- 4------ 5
    P(X=x) .18----- .22 -------.35------ a ------.13

    need some help in solving this
    not the answer jus the steps

    i solved a already
    a=.12

    find the value of a
    find the mean of the random variable X
    find the value of the E(X^2)
    find the variance the the random variable X
    find the standard deviation of the random variable X
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  2. #2
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    Quote Originally Posted by math321 View Post
    x ------ 1 ------- 2 -------3-------- 4------ 5
    P(X=x) .18----- .22 -------.35------ a ------.13
    i solved a already
    a=.12

    find the mean of the random variable X
    find the value of the E(X^2)
    Mean is E(x) = \sum\limits_x {x \cdot \mathcal{P}(x)}

    Likewise, E(x^2) = \sum\limits_x {x^2\cdot \mathcal{P}(x)}
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