Customers arrive at a barbershop at an average rate of five per hour. There is one barber on duty at all times and there are four chairs for customers who arrive when the barber is busy. Customers who arrive when the shop is full are denied entrance and their business is presumed lost. The barber's service time changes with the number of customers in the shop. The mean service time if 1 customer is in the shop is 9 minutes and increased by 1 minute if there are 2 customers. If there are 3 customers the service time is 12 minutes. With 4 customers in the shop, the service time is 15 minutes and 20 minutes if there are 5 customers. Determine: a) The average number of people in the shop at the same time; 0.1367 b) The expected time a customer must wait for service; 0.36 c) The percentage (in decimal) of time the barber is idle. Answer in 4 decimal places. 0.2400