After not doing any maths for quite a while I am more then a little rusty when it comes to probability, so I was wondering if you guys could help me.
I understand that P(A and B) = P(A) * P(B) So what is achieved by P(A)/P('A) ? I am currently trying to understand why
E(N) = p / (1 - p)
provides the expected number of users in a system?
Where p is the utilisation of the queue, given by
p = arrival rate / service rate
Am I right in assuming that p is also the probability that the system is not empty?