(Question 19-20) Consider a waiting line system. Suppose: - Customers arrive and go through the system at the rate of 10 customers per hour. - The average service time is 4 minutes. - The system has 2 customers waiting in line on average. 19. What is the average waiting time in line of a customer? A. 4 minutes B. 8 minutes C. 10 minutes D. 12 minutes E. 16 minutes 20. What is the average time spent in the system of a customer? A. 4 minutes B. 8 minutes C. 10 minutes D. 12 minutes E. 16 minutes