Let X1, ..., Xn be a random sample from a distribution with mean / and variance o2. Find the value of the following quantities (as a function of u and o2). (a) E(X1 - X2 + X3 - X4) (e) E{(X1 - X2)2 } (b) Var(X1 - X2 + X3 - X4) (f) {E(X1 - X2)}2 (c) E(4X1 - 3X2 + 2X3 - X4) (g) E(X? + X3 + ...+ X2) (d) Var(4X1 - 3X2 + 2X3 - X4) (h) E [(X1 + X2 + . .. + Xn)?]