Let X1, X2…..X10 be such that E(Xi) = 2/3 for all i, Var(Xi) = 2/9 for all i, and Cov(Xi,Xj)=-1/63 for all i and j with i=/=j. Let X=X1+ X2+…….+X10.

Find E(X) and Var(X).

I have no idea how to begin.

Thanks

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- Nov 8th 2011, 11:34 AMblackZExpected Value and Variance?
Let X1, X2…..X10 be such that E(Xi) = 2/3 for all i, Var(Xi) = 2/9 for all i, and Cov(Xi,Xj)=-1/63 for all i and j with i=/=j. Let X=X1+ X2+…….+X10.

Find E(X) and Var(X).

I have no idea how to begin.

Thanks - Nov 8th 2011, 12:00 PMmr fantasticRe: Expected Value and Variance?