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Math Help - Beta Distribution

  1. #1
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    Beta Distribution

    If i have a beta distribution with (alpha = beta = 2) then i know that the mean is 0.5 and the variance is 0.05, with SD = 0.224(3dp) from the standard rules. I am trying to find the probability that a random variable x lies within 2 SD's of the mean. so far i have got

    Pr(mean - 2Sd's < x < mean + 2Sd's)
    =Pr (0.052 < x < 0.948)

    anyone got any ideas how to find the probability from here.

    Thanks for any help.

    Tom
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  2. #2
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    Quote Originally Posted by shaky9000 View Post
    If i have a beta distribution with (alpha = beta = 2) then i know that the mean is 0.5 and the variance is 0.05, with SD = 0.224(3dp) from the standard rules. I am trying to find the probability that a random variable x lies within 2 SD's of the mean. so far i have got

    Pr(mean - 2Sd's < x < mean + 2Sd's)
    =Pr (0.052 < x < 0.948)

    anyone got any ideas how to find the probability from here.

    Thanks for any help.

    Tom
    The pdf is f(x) = 6x(x-1) for 0 \leq x \leq 1 and zero elsewhere.

    \Pr (0.052 < x < 0.948) = \int_{0.052}^{0.948} 6x(x-1) \, dx .....
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