What is the total average flow time (in minutes) of WHS, which includes both the waiting time and the time in service?

How many customers, on average will be in WHS, including both customers waiting in line and customers being served?

What is the average number of customers in service (excluding those that are waiting in line) in WHS?

If Alice goes to PHS, how long (in minutes) must she wait in line before her haircut starts?

WHS will buy out PHS. WHS will then close PHSs operations and serve all customers, including existing PHS customers, at the WHS location only. Assuming that the previous traffic of PHS customers now flows to the WHS location, what is the new inter-arrival time (in minutes) at WHS?

Alice needs to decide where to get a haircut. She has narrowed the choice down to two local hair salons Wonderland Hair Salon (WHS) and Puzzleland Hair Salon (PHS).

During busy periods, a new customer walks into WHS every 15 minutes on average, with a standard deviation of 15 minutes. At PHS, a customer walks in every hour on average, with a standard deviation of 1 hour. WHS has a staff of 4 stylists, while PHS has 1 stylist. The average service time at both salons is 30 minutes, with a standard deviation of 30 minutes.

If Alice walks into WHS during a busy period, how long must she wait in line (in minutes) before she receives a haircut? (Only include the waiting time, not any service time)