An entrepreneur provides services that can be modeled as an s-server Erlang loss (Erlang-B) system. Let's say the arrival rate is 4 customers per hour; average service time is 1 hour; the entrepreneur earns $2.50 for each customer served; and the entrepreneur's operating cost is $1.00 per server per hour (whether the server is busy or idle).

a) The optimal number of servers from the entrepreneur's point of view: ??

b) If the entrepreneur distributes the optimum number of servers, he should expect to earn $ profit per hour:

c) the maximum number of servers on which it is unprofitable for the entrepreneur to stay in business: ??