Dear all,
Assume X=$\displaystyle \left(\begin{array}{ccc}X_{11} & X_{12} & X_{13} \\ X_{21} & X_{22} & X_{23} \\ X_{31} & X_{32} & X_{33}\end{array}\right)$
How to find E(X)? where E is expected value.
Read item 6 in this reference: Expected value - Wikipedia, the free encyclopedia