Customers arrive at a Post Packages Inc. stores according to a Poisson distribution with the expected number of daily arrivals of 50. Given a random number X of customers that have arrived in a day, each such customer will either mail one package with probability 0.60, or not mail any packages with probability 0.40. Let Y be the random variable that describes the total number of packages mailed in one day. Find the difference between the variance of Y and Var (E (Y| X )) . Possible Answers