A restaurant serves three fixed-price dinners costing $12, $15, and $20. For a randomly selected couple dining at this restaurant, let X = the cost of the man's dinner and Y = the cost of the woman's dinner. The joint pmf of X and Y is given in the following table.
p(x, y)
y
12 15 20
x
12 0.05 0.35 0.10
15 0.00 0.20 0.10
20 0.05 0.05 0.10
a) Compute the marginal pmf of X.
x
12 15 20
pX(x)
b) Compute the marginal pmf of Y.
y
12 15 20
pY(y)
c) What is the probability that the man's and the woman's dinner cost at most $15 each?
d) Are X and Y independent? Justify your answer.
e) What is the expected total cost, in dollars, of the dinner for the two people?
f) Suppose that when a couple opens fortune cookies at the conclusion of the meal, they find the message "You will receive as a refund the difference between the cost of the more expensive and the less expensive meal that you have chosen." How much would the restaurant expect to refund, in dollars?