Sparagowski & Associates conducted a study of service times at the drive-up window of fast-food restaurants. The average time between placing an order and receiving the order at McDonald’s restaurants was 2.78 minutes (The Cincinnati Enquirer, July 9, 2000). Waiting times, such as these, frequently follow an exponential distribution.
a. What is the probability that a customer’s service time is less than 2 minutes?
b. What is the probability that a customer’s service time is more than 5 minutes?
c. What is the probability that a customer’s service time is more than 2.78 minutes?