A single-server queueing system has an average service time of 16 minutes per customer, which is exponentially distributed. The manager is thinking of converting to a system with a constant service time of 16 minutes. The arrival rate will remain the same. The effect will be to:
increase the utilization factor.
decrease the utilization factor.
increase the average waiting time.
decrease the average waiting time.
not have any effect since the service time is unchanged.
A small convenience store normally has one employee attending to the cash register. The average time between customer arrivals at the store is 5 minutes. The average service time at the cash register is 3 minutes. If more than two customers are standing at the register (including the customer being served), management has observed that other customers sometimes become upset and leave the store. What percentage of the time will this problem will occur?
Which of the following is not generally considered as a measure of performance in queueing analysis?
The average number waiting in line
The average number in the system
The system utilization factor
The cost of servers plus customer waiting cost
The average service time.
The Anderson Palmer Hospital would like to reduce the cost of its inventory by calculating the optimal order size for hypodermic needles. On average, the hospital uses 80 needles per month, the cost of placing an order is $14, and holding cost is estimated to be $1.20 per needle per year. Using the EOQ formula, the optimal order size is:
about 40 needles.
about 60 needles.
about 130 needles.
about 150 needles.
Which of the following is not considered a holding cost?
Stock out cost
During the early morning hours, customers arrive at a branch post office at the average rate of 45 per hour (exponential interarrival times), while clerks can handle transactions on an average of 4 minutes each (exponential). What is the minimum number of clerks needed to keep the average time in the system under 5 minutes?
A single bay car wash with an exponential arrival rate and service time has cars arriving an average of 10 minutes apart, and an average service time of 4 minutes. The utilization factor is:
None of the above
The Anderson Palmer Hospital would like to reduce the cost of its inventory by calculating the optimal order size for hypodermic needles. On average, the hospital uses 80 needles per month. The purchasing staff has calculated that the EOQ for needles is 140 needles. If they proceed to purchase in EOQ quantities, how many orders per year will be placed?
About 6 orders per year
About 7 orders per year
About 9 orders per year
About 10 orders per year
If a manager increases the system utilization standard (assuming no change in the customer arrival rate) what happens to the average customer time in the system?
It increases exponentially.
It increases proportionally.
It decreases proportionally.
It decreases exponentially.
It does not change.
As the ratio of arrival rate to service rate is increased, which of the following is likely?
Utilization increases and customers must wait longer in the queue.
Utilization is decreased because of the added strain on the system.
The average number in the system decreases.
Customers move through the system in less time because utilization is increased.
None of the above.
The term queue discipline refers to:
the willingness of customers to wait in line for service.
having multiple waiting lines without customers switching from line to line.
the order in which customers are processed.
the reason waiting occurs in underutilized systems.
None of the above.
The goal of the basic EOQ model is to:
minimize the sum of setup and holding costs.
minimize the sum of purchasing and setup costs.
minimize order size.
minimize order cost.
minimize holding cost.