Expected time in queue of customer of class k who has just arrived at system k-1 Wak=Wot Lo:+ =1i Wo=expected remaining time in service of the customer who occupies the server when the new customer(from class k) arrives e9=expected no of customers of class who are already waiting queue at the instant when the newly arrived customer(from class arrives M;= expected number of customers of class i who will arrive while the newly arrived customer(from class k) is waiting in queueExpected time in queue of customer of class k who has just arrived at system å å - = = = + × + × 1 1 1 0 1 1 k i i i k i qi i Wqk W L M m m W0 = expected remaining time in service of the customer who occupies the server when the new customer (from class k) arrives Lqi = expected no. of customers of class i who are already waiting in queue at the instant when the newly arrived customer (from class k) arrives Mi = expected number of customers of class i who will arrive while the newly arrived customer (from class k) is waiting in queue