Abstract
An approximation formula for the mean waiting time of an M/G/c. queue is proposed. It estimates the mean waiting time from a moment of order α≦2, rather than the second moment, of the service distribution. Together with the Lee & Longton's formula [1] and the Page's formula [2] , it was numerically tested on a variety of cases, and the test shows that the new formula is generally better than the previous two formulas, especially for queues with mixtures of Erlang distributions as the service distribution. A similar approximation formula for the variance of the waiting time is also proposed.
