Joe finds that, when he waits for a bus, his waiting time is Exponential, with an average waiting time of 6 minutes. Assume that he waits for one bus in the morning and again for one bus in the evening.
a. What is the probability that he spends 15 minutes or less at the bus stop altogether during the day?
b. What is his expected waiting time at the bus stop (mornings and evenings included) during a 20 day period?
c. What is the approximate probability that he spends 200 minutes or less at the bus stop during a 20 day period (again, mornings and evenings included)?