Answer Happy

4. A certain market has both an express checkout line and a superexpress checkout line. Let X denote the number of customers in line at the express checkout at a particular time of day, and let. Y denote the number of customers in line at the superexpress checkout at the same Lime. Suppose the joint pmlp of X and Y is given by the table P p(y) 0 1 2 3 4 0 1 2 3 0.08 0.07 0.04 0.00 0.06 0.15 0.05 0.04 0.05 0.04 0.10 0.06 0.00 0.03 0.04 0.07 0.00 0.01 0.05 0.06 For example, Pr(X -1,7 -0 0.06. (1) What two conditions guarantee that p is a valid pmfy (b) What is the probability that there is exactly one customer in each line (c) What is the probability that the numbers of customent in the two linear (a) What is the probability that there are at least two more ctitomen in the superexpose chuckout line than in the express checkout line? (e) What is the probability that the total number of customen in the two lines in four!