Customers arrive at an automated coffee vending machine at a rate of 4 per minute, following a

Question:

Customers arrive at an automated coffee vending machine at a rate of 4 per minute, following a Poisson distribution. The coffee machine dispenses a cup of coffee at a constant rate of 10 seconds.
(a) What is the average number of people waiting inline?
(b) What is the average number of people in the system?
(c) How long does the average person wait in line before receiving service?