MacBurger’s is attempting to determine how many servers to have available during the breakfast shift. On average, 100 customers arrive per hour at the restaurant.

Each server can handle an average of 50 customers per hour. A server costs $5 per hour, and the cost of a customer waiting in line for one hour is $20.

Assuming that an M
M
s model is applicable, determine the number of servers that minimizes the expected sum of hourly delay and service costs.