A cafeteria serving line has a coffee urn from which customers serve themselves. Arrivals at the urn follow a Poisson distribution at the rate of 4.0 per minute. In serving themselves, customers take about 11 seconds, exponentially distributed. a. How many customers would you expect to see, on average, at the coffee urn? (Do not round intermediate calculations. Round your answer to 2 decimal places.)

b. How long would you expect it to take to get a cup of coffee? (Round your answer to 2 decimal places.)

c. What percentage of time is the urn being used? (Do not round intermediate calculations. Round your answer to 1 decimal place.)

d. What is the probability that three or more people are in the cafeteria? (Do not round intermediate calculations. Round your answer to 1 decimal place.)