Hi!

Problem: A die is rolled twice. Let $\displaystyle X$ denote the sum of the two numbers that turn up, and $\displaystyle Y$ the difference of the numbers (specifically, the number on the first roll minus the number on the second roll). Show that

$\displaystyle E(XY)=E(X)\cdot E(Y) $

Are $\displaystyle X$ and $\displaystyle Y$ independant?

Thanks