Suppose that X and Y are random variables such that E(Y | X) = 7 - (1/4)x E(X | Y) = 10 - Y . Determine the correlation of X and Y . Solution We know that cor(x,y)=cov(x,y)/(v(x)v(y))^.5 here we are given with p@Y/@X and p@X/@Y thus on solving we get cor(x,y) =0.5 here @ =sigma.