1. Let X, and X2 be random variables with mean / (same for both). a. What is the mean of X1+ X2 ? What about (X1+X2)/2? b. Suppose X1, X2 ,...,XN are N random variables each with mean J . What is the mean of N Ex, ? i c. Suppose X, and X2 are independent with the same variance, - . Find Var (X1 + X2 Hint: You will need to use two facts about variances. First, If X, and X2 are random variables with variances of and oz , then the variance of X +X2 is Var X1+X2 =oj+03+2 Cov(X1, X2), Second, Var ax = a-Var (x d. Suppose X1, X2,..., XN are N random variables each with mean # and variance o2 . What is Var . V