Exam 18: Management of Waiting Lines

Two troubleshooters handle service calls for 10 machines.The average time between service requirements is 18 days, and service time averages 2 days.Assume exponential distributions.While running, each machine can produce 1,500 pieces per day.Determine: (A) the percentage of time troubleshooters are idle (B) each machine's net productivity (C) If troubleshooters represent a cost of $150 per day, and machine downtime cost is $600 per day, would another troubleshooter be justified? Explain.

Waiting lines occur even in under loaded systems because of variability in service rates and/or arrival rates.

A manager assembled the following information about an infinite source waiting line system: 5 servers, an arrival rate of 6 per hour, and a service time of 20 minutes.The manager has determined that the average number of customers waiting for service is 0.04.Determine each of the following: (A) the system utilization (B) the average waiting time in line in minutes (C) the average time in the system (D) the average number in the system

A single phase queuing system is one which has a single:

Offering an "early bird" special at a restaurant to reduce waiting times during peak hours is an example of ____________.

In a multi-channel system with multiple waiting lines, customers shifting among the waiting lines is an example of __________.

What is the average time that player's card holders wait to be seated?

What is the probability that a machine will have to wait for service with two operators?

If a manager increases system utilization (assuming no change in the customer arrival rate) what happens to the customer waiting time?

Servers, channels are described with many acronyms except _________.

The queuing models discussed in the text apply only to "steady state" conditions.Steady state exists only when customers arrive at a steady rate; that is, without any variability.

A multiple channel system has customers arriving at an average rate of five per hour and an average service time of forty minutes.The minimum number of servers for this system to be under loaded is:

The goal of waiting line management is to minimize waiting time.

The goal of waiting line management is to eliminate customer waiting lines.

What is average time in line for a high priority item?

Little's Law states that the number of people in a waiting line is the average customer arrival rate multiplied by the ________.

What is average time in line for a low priority item?

A department has 5 semiautomatic pieces of equipment which operate for an average of 79 minutes before they must be reloaded.The reloading operation takes an average of 21 minutes per machine.Assume exponential distributions. (A) What is the minimum number of servers needed to keep the average downtime per cycle to less than 25 minutes? (B) If 1 server is used, what percentage of time will the machine be down?

According to Little's Law, the number of people in line depends on the time of day that they arrive.

Which of the following would reduce perceived waiting times most dramatically in a doctor's office?