Variance problem

Discussion in 'Math' started by boks, Jan 28, 2009.

  1. boks

    Thread Starter Active Member

    Oct 10, 2008
    218
    0
    A probability distrubution is given by

    f(x) =

    x, 0 < x < 1
    2-x, 1 <= x <2
    0, elsewhere

    Find the variance of X.


    I first calculate the expected value:

    E(X) = \int^{1}_{0}x^2 dx + \int^{2}_{1}2x - x^2 dx = 1

    Then the variance:

    \sigma^2 = \int^{1}_{0}(x-1)^2x dx + \int^{2}_{1}(x-1)^2(2-x) dx = 1/6
     
    Last edited: Jan 28, 2009
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