Abstract
This paper is concerned with a system of two queues in tandem where each queue has a single exponential server. The rates. of the servers may differ. The first queue has an infinite waiting room, whereas the second queue has no waiting room. Initially the system is empty. Customers enter the first queue according to a renewal input process, and then pass through the second queue. We are concerned with the sojourn time of a customer in the system. We show that the queues are interchange-able, in the sense that the order of queues does not affect the sojourn and delay distributions.
