1.) The joint distribution of two discrete random variables can be described using the joint pmf. (True/False)

2.) Joint CDF of two random variables, 1 and 2, is equal to the (1)(2). (True/False)

3.) A linear function of a normal random variable is still normally distributed. (True/False)

4.) A linear function of an exponential random variable (X), U=aX+b, is still exponentially distributed. (True/False)