math plz plz help
2007-10-01 7:43 am
A random variable X assumes the value 1 with probability pai( the thing=3.1415) and 0 with probability (1-pai).Prove that E(X) = pai, Var (X) = pai(1 - pai).
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2007-10-01 10:37 am
✔ 最佳答案
A random variable X assumes the value 1 with probability pai( the thing=3.1415) and 0 with probability (1-pai).Prove that E(X) = pai, Var (X) = pai(1 - pai). E(X)= Σxp(x)=1*π+0*(1-π)=π
E(X^2)= Σx^2p(x)=1*π+0*(1-π)=π
Var (X) =E(X^2)-[E(X)]^2=π-π^2=π(1-π)
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