Random variables x and y are independent with PDF's
fx(X) = { 1/3 e^(-x/3) x ≥ 0,
0 otherwise
fy(Y) = { 1/2 e^(-x/2) y ≥ 0,
0 otherwise
a. Find P(x > y). b. Find E[xy]. c. What is Cov(x,y)?