At a Mexican fast-food chain, a customer a) decides what type of food s/he wants (e.g., burrito, salad, or tacos), b) decides what fillings s/he wants (e.g., chicken, fish, or vegetable), c) decides what toppings s/he wants (e.g., lettuce, guacamole, or cheese), and d) pays for the order that may or may not include a drink.
One employee works at each of the steps a) through c), and two employees take care of the payment. Per customer, step a) takes 2 minutes on average, step b) takes 3 minutes on average, step c) takes 1 minute on average, and step d) takes 4 minutes on average. Suppose another person is hired for step b), what is the system capacity?
A) 30 customers/hour
B) 40 customers/hour
C) 60 customers/hour
D) 20 customers/hour