A service station has both self-service and full-service islands.

On each island, there is a single regular unleaded pump with two hoses. Let X denote the number of hoses being used on the self-service island at a particular time, and let Y denote the number of hoses on the full-service island in use at that time. The joint pmf of X and Y appears in the accompanying tabulation.

a. What is P(X
1 and Y
1)?

b. Compute P(X  1 and Y  1).

c. Give a word description of the event {X 0 and Y 0}, and compute the probability of this event.

d. Compute the marginal pmf of X and of Y. Using pX(x), what is P(X  1)?

e. Are X and Y independent rv’s? Explain.