How much will expect to gain/lose?

Question

Ace's Pizza delivers several types of pizza, which is sold for 499 php and cost 300 php to make. The pizza shop has a policy that no charge will be asked if the delivery takes longer than half an hour. Experience has shown that delivery takes longer than half an hour only 10% of the time. How much will the pizza shop expect to gain/lose in return?

Answer 1

net is delivered on time = 499 - 300 = 199, 90% of the time

net if not delivered on time -300, 10% of the time

expected gain/loss = 199 * 0.90 - 300 * 0.1 = 149.10 expected gain