is this model following a M/Ms queuing model?? or M/g/s model?? please look at the info given. They say mean service time of 2minutes, but they also give standard deviation of 1.25 min.

why would they also say service time is exponentially disttibuted but then give a standard deviation?

please dont copy previous stuff try tpe explain to me please

The problem at hand relates to a waiting time management of queues in a typical bank. In a bid to improve the level of service at the tellers, a bank manager seeks to find strategies to employ for better service offering that will improve customer satisfaction. The manager is prepared to employ up to 5 cashiers, but not less than 1 . The main management objectives are (i) To have a average customer to wait less than 2 minutes for service, and (ii) the average length of the queue (waiting line) to be 2 persons or fewer. The manager tests several models to help in the decision process. Model 1 Suppose the manager makes the following assumptions: - The distribution of the length of time it takes the cashiers to carry out a service is exponential, with mean 2 minutes and standard deviation of 1.25 minutes; - There is no limit to the queue length during business hours as the bank has a large floor area; - Customers arrive is a Poisson distribution, with mean of 25 per hour - Service is done on a first come first serve basis