A delicatessen located in the heart of the business district of a large city serves a variety of customers. The delicatessen is open 24 hours a day every day of the week. In an effort to speed up take-out orders, the deli accepts orders by fax. If, on the average, 20 orders are received by fax every two hours throughout the day, find the
a. probability that a faxed order will arrive within the next 9 minutes.
b. probability that the time between two faxed orders will be between and 3 and 6 minutes.
c. probability that 12 or more minutes will elapse between faxed orders.