Discuss the below in detail:
Q: A small company just opened a new massage station at Philadelphia airport. The company has a stand that offers massage to travelers. Customers can select a length of massage between 5 and 20 minutes and there is a unique rate of $30 independently of the length selected by customers. The average length of massage request by customers is of 15 minutes with standard deviation of 10 minutes. There are two employees delivering massage. The average of potential customers requesting a massage is of 20 per hour. The inter-arrival times are assumed to be exponentially distributed. If no spot is available when the customer arrives, she leaves in order not to risk missing her his flight. What is the average number of customers serviced per how?