The registration area has just opened at a large convention of building contractors in Banff. There are 75 people arriving per hour (Poisson distributed), and the cost of their waiting time in the queue is valued at $35 per person per hour as while waiting they are able to watch a juggler who keeps them entertained. The juggler is paid $18 per hour. The local convention bureau provides servers to register guests at a fee of $45 per person per hour. It takes about three minute(s) to register an attendee (exponentially distributed). A single waiting line, with multiple servers, is set up. a) What is the optimal number of servers? The optimal number of servers is (Enter your response as a whole number.) b) What is the cost for the system, per hour, at the optimal service level? For the optimum number of servers, the total cost per hour is $ (Enter your response rounded to the nearest dollar.)