Q. Travellers arrive at the main entrance door of an airline terminal. There are 2 types of customers regular and frequent flier. The time among arrivals of regular customers is exponentially distributed with a mean of 2 min. The time among arrivals of regular fliers is also exponentially distributed with a mean of 4 min. At the check in counter, travellers wait in a single line until one of the 5 agents is available to serve them. The check in time follows a regular distribution.