2. The number of days ahead of time that travelers purchase their airline tickets can be modeled by an exponential distribution with A = 1 (a) (4 points) What is the expected value of the number of days ahead of time a traveler will purchase an airline ticket? What is the variance of the number of days ahead of time a traveler will purchase an airline ticket? What is the standard deviation of the number of days ahead of time a traveler will purchase an airline ticket? (b) (5 points) Find the probability that the number of days ahead a traveler will purchase an airline ticket is between 10 and 16 days. (c) (6 points) Given that the number of days ahead of time a traveler will purchase an airline ticket is more than 7 days, what is the probability that the number of days the traveler purchases the ticket is more than 9 days? Page 2