Final answer:
Lunches should be delivered within 10-20 minutes after guests order, with 15 minutes being an ideal standard. This accounts for a steady customer flow and the need for efficiency between classes.
Step-by-step explanation:
The question is related to the service time and customer satisfaction in a restaurant context. Given the scenario that it is between classes and not peak lunch time, a reasonable time for lunches to be delivered after the guests order would be within 10-20 minutes. This would account for time sensitivity due to classes. Also, from the given information that one customer arrives every two minutes on average, it can be deduced that the establishment experiences a steady flow of customers, suggesting the staff would be accustomed to a consistent pace of service.
Hence, 15 minutes could be a suitable standard for delivery of food after guests have ordered. This time frame allows the kitchen and service staff to prepare and deliver a quality meal without making the guests feel rushed or causing them to be late for their next class.