I am just in the midst of examn preparation and ask myself if somebody could help me with the following queueing problem:
A local country garage has one petrol pump. On average, customers are served at a rate of 6 per minute. On normal days, customers arrive at the rate of 30 every 10 minutes. Arrivals follow a Poisson distribution and service times follow an exponential distribution.
a. What is the average number of customers in the queue?
Hint:
Relevant formula: $$\rho = \frac{\lambda}{\mu}$$ $$N(M/M/1)=\frac{\rho}{1-\rho}$$