I'm having troubles with the basics here--do I use exponential process or poisson? Suppose a queueing station has two servers, an exponential inter-arrival time for customers with a mean of 2 hours and an exponential service time for service with mean of 2 hours. Furthermore a customer has just arrived at 12 noon. 1. What is the probability that the next arrival will be before 1:45pm? I have tried using exponential distribution with lambda = 0.5...but can't figure out what I'm doing wrong. Thanks.