20. Let (X,Y') be two random variables such that standard deviation of X is 2 and covariancebet
問題詳情
20. Let (X,Y') be two random variables such that standard deviation of X is 2 and covariancebetween X and Y is 2. What is the covariance between 3X and X + 3Y? (A) 21； (B)10； (C)25； (D)16； (E)30.