The Average Waiting Time for Patients Arriving at the Newtown

Multiple Choice

The average waiting time for patients arriving at the Newtown Health Clinic between 1 P.M. and 4 P.M. on a weekday is an exponentially distributed random variable x with expected value of 30 minutes. What is the probability that a patient arriving at the clinic between 1 P.M. and 4 P.M. will have to wait between 27 and 32 minutes?
Round your answer to two decimal places.

A) 0.31
B) 0.16
C) 0.17
D) 0.06