The random variable X represents the number of phone calls a CFO receives in a day, and it has a Poisson distribution with a mean of 8.1 calls. (a) What are the possible values of X? |0, 1, 2, 3,... (b) Is a value of X=3.7 possible? Why or why not? A value of X=3.7 is not possible because X is a discrete random variable. (c) What is the expected number of phone calls in 4 days? (d) Why is it okay for the expected number of phone calls to have a decimal, but not for the value of X? The expected value is an average and averages can take any value. X describes the number of phone calls and you cannot have part of a phone call.