and in this usage it must be remembered that W is defined as mean response time, the mean time spent in the queue and at the server, and not just simply as the mean time spent waiting to be served, L refers to the average number of customers
in the system and λ is the mean arrival rate. Little’s law can be applied when we relate L to the average number of customers waiting to receive service, Lq and W to the mean time spent waiting for service, Wq, that is another well-known form is