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Variance of the random variable $X$ is$4$ .Its mean is $2.$ Then $E(X^{2})$ is

\[\begin{array}{1 1}(1)2&(2)4\\(3)6&(4)8\end{array}\]

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Given $Var(X) =4,E(X)=2$
$Var(X) =E(X^2) -[E(X)]^2$
$4= E(X)^2-2^2$
$E(x^2) =4+4=8$
Hence 4 is the correct answer.
answered May 23, 2014 by meena.p
 

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