At the bank teller's window, arrivals and service times are randomly distributed (Poisson and exponential distributions, respectively). There is only one teller at the window. If the arrival rate is 8 customers per hour, and the service rate is 14 customers per hour, what is the average length of queue in front of the teller? (It is a single channel, single server, single phase, unlimited waiting space model) (Note: we need Lq, not Ls)