The benefits of applying queueing theory to analyze business processes is that they provide the analyst with insight into the performance of business processes, and the performance analysis can be conducted rapidly, allowing for fast generation of alternative process designs. One of the most important purposes of studying queuing theory is to find a balance between these two costs, that is, the waiting cost and the service cost. There are varieties of queuing models that arise from the elements of a queue. The pure birth model considers only arrivals, and the inter-arrival time in the pure birth model is explained by the exponential distribution. The pure death model contradicts the pure birth model, in the sense that only departures are considered in this model. Generalized poisson queuing model considers both interarrival time and service time, and both these times follow exponential distribution.