1. The problem statement, all variables and given/known data let y_1 and y_2 be iid bin(5,1/4) random variables let v=y_1+2*y_2 and u = 3*y_1 -2y_2 find f_uv (u,v) and the cov(u,v) 2. Relevant equations f_y (y) = (5 choose y) (1/4)^y (3/4)^5-x for x=0,1,2,3,4,5 covariance=E(uv)-E(u)E(v) 3. The attempt at a solution By convolution the Sum of bin(n,p) and bin(m,p) = bin (n+m,p) so pdf of v = bin(15,1/4) and pdf of u = bin (5,1/4) The only way I know of to get the joint pdf is by a table. Is there a faster way?