A Doctors office is a single-server waiting line system and has an arrival pattern characterized by a Poisson distribution with 3 customers per hour. The average service time is 12 minutes. The service times are distributed according to the exponential distribution.

1. Length of time customer waits in the system

   	a.	18
   	b.	30
   	c.	36
   	d.	60

2. ^{What happens to the customer waiting time if system utilization increases?}

   	a.	increases exponentially
   	b.	increases proportionally
   	c.	decreases exponentially
   	d.	decreases proportionally

3. ^{Which of the following will not decrease system utilization?}

   	a.	increase in the number of servers
   	b.	decrease in service time
   	c.	increase in arrival rate
   	d.	increase in service rate

4. A drive thru car wash can process cars at a rate of one every five minutes. The manager notices that during one particular day it takes cars an average of about 30 minutes in line to reach the car wash. What was the average number of cars in line on that day?

   	a.	7 to 9 cars
   	b.	1 to 3 cars
   	c.	10 or more
   	d.	4 to 6 cars

Thank you!