Suppose that X is a random variable with mean 30 and standard deviation 10. Also suppose that Y is a random variable with mean 20 and standard deviation 8. Assume that the correlation between X and Y is 0.4. Find the mean and standard deviation of the random variable Z for each of the following cases. Be sure to show your work. a. Z= 2 + 10X. b. Z = X + Y. c. Z = −5X − 3Y