2. Let X1 and X2 be independent random variables with pdf's fi(x1) = 2x1, 0 < x1 < 1, and f2(x2) = 4x2, 0 < x2 < 1, respectively. Compute (a) P(0.5 < X1 < 1 and 0.4 < X2 < 0.8) (b) E[XX] 3. Assume X1, X2, X3, X4 is a random sample of size n = 4 from the normal distribution N(75 100)