The computer lab at State University has a help desk to assist students working on computer spreadsheet assignments. The students patiently form a single line in front of the desk to wait for help. Students are served based on a rst-come, rst-served priority rule. Students arrive at the help desk at the rate of 4 every 10 minutes. The average service time is 2 minutes. The Poisson distribution is appropriate for the arrival rate and service times are exponentially distributed.

a) What is the average time a student is in the lab?

b) What is the average number of students in the lab?

c) What is the average number of students waiting to receive service?

d) What is the average time a student is in the queue?

e) What is the probability that there are no students at the computer lab?

f) What percentage of the time is the help desk busy?

g) What is the probability that there are exactly 2 students in the lab?

h) By how much would your answer to part (a) be reduced if a second help desk, which could do the same work, were added?