Scotiabank is the only bank in the small town of St. Thomas. On a typical Friday, an average of 10 customers per hour (Poisson distribution) arrive at the bank to transact business. The are two tellers at the bank and the average time required to transact business is four minutes. It is assumed that service time is described by the exponential distribution. A single line would be used and the customer at the front of the line would go to the first available teller. What is the average number of customers in the line.