2. (24 points) Let W1 and W2 be I.I.D. RV's with fw. (wi) = e-Wiu(wi), where u(wi) is the unit step function which implies the pdf is valid only for values of wi 2 0. (a) (8 points) Derive the joint pdf of X, Y, where X = W1 + W, and Y = Wi. W2(b) (8 points) Derive the marginal pdf of X.(c) (8 points) Derive the marginal pdf of Y