Detailed solution please

[10] 4. Let X ~ N(3, 2") and Y ~ N(1, 3") be independent random variables. Let W = X - 2Y. [4] a. Find E(W) and the standard deviation of W. 3] b. Find P[W> > 9]. [3] b. Find E(W") for n = 2.3,4. (you may use the Gamma function and the fact that every normal random variable can be written as a linear function of a (0, 1) random variable Z, that is W = a+6Z for constants a, b where Z ~ N(0, 1) )