Suppose I have two independent coins and I flip each of them for once. Let Xi=1 (= 1,2) if the i th coin turns to be head: Xi=O_if tail. It is known that P(X1 - 1) =P(XI-0) = 0.5 and P(X2 = 1) = 0.6.P(X2 - 0) - 0.4 1-Define new random variable X3 = X1 -X2. 1) What distribution does X1 follow include the value of the parameters), if any)? How about X2? 2) Show the pmf of X3. 3) Compute E(X1 ), E(X2 ), and E(X3). 4) Compute V(X1 ),W(X2 ), and V(X3 )