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Math Help - finding the p.m.f

  1. #1
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    finding the p.m.f

    Let the pmf of X be defined by f(x)=6/((pi^2)(x^2)), x=1,2,3....

    show that E(X) does not exist (Can you show that f(x) is a p.mf.?)

    And I know that x^-2 converges to Pi^2/6 ..
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  2. #2
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    Quote Originally Posted by calculuskid1 View Post
    Let the pmf of X be defined by f(x)=6/((pi^2)(x^2)), x=1,2,3....

    show that E(X) does not exist (Can you show that f(x) is a p.mf.?)

    And I know that x^-2 converges to Pi^2/6 ..
    \displaystyle E(X) = \sum_{x = 1}^{+\infty} x f(x). Does this series converge ....?
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  3. #3
    MHF Contributor matheagle's Avatar
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    Quote Originally Posted by calculuskid1 View Post
    Let the pmf of X be defined by f(x)=6/((pi^2)(x^2)), x=1,2,3....

    show that E(X) does not exist (Can you show that f(x) is a p.mf.?)

    And I know that x^-2 converges to Pi^2/6 ..
    I assume you mean the sum converges to \pi^2/6
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