The flow chart above shows a process where two flows of customers come to a cashier process and get into the queue. The arrival rate is 0.167 customer/minute from one flow and 0.067 per minute from the second flow. On average 2 customers are in line waiting for the cashier to start and on average it takes a cashier 5 minutes with each customer.

On average how long do customers wait in line for the cashier?

Enter R= 4 customer/hour R= 0.067 cust/min. Enter Cashier R= 10 customer/hour R= 0.167 cust/min. Exit Wait for cashier customers R= T= min 5 min