Service times:
A) In most cases, servicing a request takes a “short” time, but in a few occasions requests take much longer.
B) The probability of completing a service request by time t, is independent of how much time has already passed. We should not expect this property to hold in situations where the server must perform the same fixed sequence of operations for each customer, because then a long elapsed service should imply that probably little remains to be done. However, in the type of situation where the required service operations differ among customers, the property may be quite realistic. For in this case, if considerable service has already elapsed for a customer, the only implication may be that this particular customer requires more extensive service than most
C) Corollary:
- The number of service completions in an interval is characterized by a Poisson distribution.