A bank that recently opened its doors, has decided to install an ATM that retains people who wish to make a single deposit; in a recent study of the operation of that type of ATM in another entity, it was observed that the service time is constant with 6.5 minutes. To determine the operating characteristics of this new cashier, people's arrivals have been evaluated and it has been found that they behave in the form of Poisson distribution at the arrival of 3 people per hour: 

A. Determine the behavior of the system. 

B. the waiting time cost is $4.5 and the service cost is $5.8 per hour. Determine the total cost by time period.