Cynthia​ Knott's Car Wash is open 6 days a​ week, but its busiest day is always Saturday. From historical​ data, Cynthia estimates that dirty cars arrive at the rate of 20 per hour all day Saturday. With a full crew working the​ hand-wash line, she figures that cars can be cleaned at the rate of one every 2 minutes. One car at a time is cleaned in this example of a​ single-channel waiting line. Assume Poisson arrivals and negative exponential service times.