Consider an Espresso Stand with a Single Barista

Multiple Choice

Consider an espresso stand with a single barista. Customers arrive to the stand at the rate of 28 per hour according to a Poisson distribution. Service times are exponentially distributed with a service rate of 35 customers per hour. The probability that the server is idle and a customer may be served is

A) 0.20.
B) 0.60.
C) 0.80.
D) 1.00.