Cancelled flights. Mary is deciding whether to book the cheaper f light home college after her final exams, but she’s unsure when her last exam will be. She thinks there is only a 20% chance that the exam will be scheduled after the last day she can get a seat on the cheaper f light. If it is and she has to cancel the f light, she will lose $150. If she can take the cheaper f light, she will save $100.

a) If she books the cheaper f light, what can she expect to gain, on average?

b) What is the standard deviation?