4. Suppose that Xi, 2, , x, are independent randomi variables that each come from the same distribution. For example, each of them might come from Bin 100, 0.25) or each of them might come from Unif(1.6). Suppose that EXi- and Var(Xi)- 2 for 1 i n. Define another random variable M to be the average value of (a) Derive and simplify a formula for EIM) as a function of n, , and . (b) Derive and simplify a formula for Var(M) as a function of n, , and