Customers arrive at a bank counter manned by a single cashier according to a Poisson distribution with a mean arrival rate of 6 customers per hour. The cashier attends to the customers on a first-come, first-serve basis at an average rate of 10 customers per hour, with the service time exponentially distributed. Find the probability of the number of arrivals (0 through 5) during (i) a 15-minute interval, (ii) a 30-minute interval. Also, find the probability that the queuing system is idle, the probability associated with the number of customers (0 through 5) in the queuing system, the probability that there are more than 3 customers in the queuing system, the time a customer should spend in the queue, and the time a customer spends before leaving the bank counter.