Information desk. A university librarian notices that the arrival rate at the university library information desk is about five people per hour and that there is no apparent relationship between consecutive arrivals.

a) What model might you use to model the number of arrivals at the university library information desk per hour?

b) What model would you use to model the time between arrivals at the information desk?

c) What would the probability be that the time to the next arrival at the desk is 15 minutes or less?

d) What is the mean time between arrivals?