I can't seem to get the same answer as the back for this question. Can someone show me how to properly do it?
Let X and Y be two independent random variables where E(X) = 4, E(X^2)= 20 and V(Y)= 21. Find:
(a) V (X + 3Y)
(b) the standard deviation of (X+ + 3Y)
The answers at the back are 193 and 13.9.