Answer : 8 minutes
As 10 customer arrive per hour the arrival rate is 10 cars per hour. As each customer takes 4 minutes to be serves, in each hour 60/4 = 15 customers can be served.
Hence = 10 and = 15
Average time a customer spends in the waiting line, Wq is given as below
Hence waiting time in queue is 0.1333 hours or 0.1333*60 = 8 minutes
For the Starbucks Coffee Company stores in Beijing, China, using the Poisson distribution, corporate management back...