X1 and X2 are two random variables that are jointly distributed such that E(X1) = 6, E(X2) = 8, Var(X1) =5, Var(X2)=2 and Cov(X1,X2)= -1. Let average of X score = x1+x2 / 2.

1. Compute E(average of x).
2. Compute Var (average of x)
3. Compute Corr (x1,x2)

Any help is appreciated. Also is there a way to do this on excel. Thanks