A restaurant already has the single line/three server system in place, with Poisson arrivals at a rate of 30 per hour and exponential service at a rate of 15 per hour. To maintain its stellar customer service reputation, the restaurant is considering the addition of a fourth server. To justify the cost of adding a new server, the restaurant decides that it will add a fourth server only if, in the current system, the following two conditions hold: the probability of a customer having to wait for service is above 0.25 and the probability of the system being empty is below 0.1. Based on these criteria, should the restaurant add the fourth server? Why or why not?