Deck 24: Management of Waiting Lines

Question 1

A single-server, variable-service-time system is known as an M/D/1 system.

Answer 1

False

Question 2

The cost of customer waiting is easy to estimate, the number waiting multiplied by the wait cost per minute.

Answer 2

False

Question 3

All infinite-source queuing models require the system utilization to be less than 1.0.

Answer 3

True

Question 4

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.

Question 5

To reduce the average number waiting in line, it is important to increase utilization.

Question 6

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

Question 7

An approach to reducing the variability in processing times might include greater standardization.

Question 8

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

Question 9

A multiple-channel system assumes that each server will have its own waiting line, and line changing is not permitted.

Question 10

A dental office with two professionals (one dentist, one hygienist) who work together as a team would be an example of a multiple-channel system.

Question 11

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

Question 12

For a system that has a low utilization ratio, decreasing service capacity slightly will have only negligible effect on customer waiting time.

Question 13

The point that minimizes total queuing system costs is that point where waiting costs and capacity costs are equal.

Question 14

The most commonly used queuing models assume that the arrival rate can be described by a Poisson distribution.

Question 15

In a theme park like Disney world, reservation systems are a win-lose situation since only those holding reservations are satisfied.

Question 16

A system has one service facility that can service 10 customers per hour. The customers arrive at a variable rate, which averages six per hour. Since there is excess capacity, no waiting lines will form.

Question 17

In an infinite-source model, the system utilization is the ratio of the arrival rate to the service capacity.

Question 18

In an infinite-source model, the average number being served is equal to the ratio of the arrival rate to the service rate.

Question 19

The goal of queuing analysis is to balance the cost of providing a level of service capacity with the possible loss of business due to customers leaving the line or refusing to wait.

Question 20

In an infinite-source model, the average time in line is equal to the average number in line divided by the arrival rate.

Question 21

Queue discipline requires a security presence to maintain order.

Question 22

In a _______ system, customers enter the waiting line, receive service, and leave.

A) fast-track
B) simulated
C) queuing
D) random
E) non-random

Question 23

Each of the following is notation for a waiting-line model presented in the textbook except:

A) M/P/S.
B) M/M/1.
C) M/D/1.
D) M/M/S.
D) M/M/S.

Question 24

Although it is generally the case that service systems have enough capacity, waiting lines result when __________ exceeds capacity for periods of time.

A) homogeneity
B) variability
C) price
D) demand
E) heterogeneity

Question 25

As the ratio of arrival rate to service rate is increased, which of the following is likely?

A) Customers move through the system in less time because utilization is increased.
B) Customers move through the system more slowly because utilization is increaseD.
C) Utilization is decreased because of the added strain on the system.
D) The average number in the system decreases.
E) There really is no change since arrival rates are offset by service rates.

Question 26

The total cost curve:

A) starts at zero and increases as service capacity increases.
B) begins high and decreases as service capacity increases.
C) starts high, declines, then increases again.
D) remains relatively flat regardless of service capacity.
E) starts at zero, increases rapidly, then declines slowly back to zero.

Question 27

The value of standardizing some or all of a service is demonstrated by the shorter wait times observed in models with:

A) constant demand rates.
B) finite queues.
C) infinite sources.
D) finite sources.
E) constant service times.

Question 28

Why is there waiting in an infinite-source queuing system?

A) poor scheduling of servers
B) slow service
C) low utilization
D) variability in arrival and service rates
E) multiple-phase processing

Question 29

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

A) channel.
B) server.
C) customer being served.
D) operation.
E) waiting line.

Question 30

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

A) average time in the system.
B) average waiting timE.
C) service time minus the waiting time.
D) average number in line.
E) waiting time.

Question 31

Which of the following is not generally considered to be a measure of system performance in a queuing analysis?

A) the average number waiting in line
B) the average number in the system
C) system utilization
D) the cost of servers plus customer waiting cost
E) average serving time

Question 32

In which of these settings would one be least likely to encounter first-come service?

A) a fast-food restaurant
B) a doctor's office
C) a hotel check-in operation
D) an emergency room
E) a check-out line

Question 33

A single-channel queuing system has an average service time of eight minutes and an average time between arrivals of 10 minutes. The arrival rate is:

A) 6 per hour.
B) 7.5 per hour.
C) 8 per hour.
D) 10 per hour.
E) 12.5 per hour.

Question 34

A customer growing frustrated with the wait and leaving the facility (without being served) is an example of:

A) reneging.
B) utilizing.
C) balking.
D) jockeying.
E) departing.

Question 35

Which of the following would tend to increase the difference between the actual time customers spent waiting and the perceived time spent waiting by those customers?
(I) Lots of experience with the service on the part of customers
(II) Anxiety on the part of customers
(III) A pleasant physical environment for the customers

A) I and II only
B) I only
C) II only
D) III only
E) I, II, and III

Question 36

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

A) It increases exponentially.
B) It increases proportionally.
C) It decreases proportionally.
D) It decreases exponentially.
E) No change.

Question 37

Compared to a single-channel system with exponential service time, a single-channel system with a constant service time causes a reduction of 50 percent in the average number waiting in line.

Question 38

A basic difference between infinite-source and finite-source queuing models is the:

A) number of servers.
B) average waiting time.
C) arrival distribution.
D) size of potential calling population.
E) processing rate.

Question 39

To reduce waiting times by actively managing system constraints, managers could consider:
(I) using temporary workers.
(II) shifting demand from high-demand periods to low-demand periods.
(III) offering more service variety.
(IV) discovering bottlenecks.

A) I and III only
B) I, II, and IV only
C) III only
D) II and IV only
E) IV only

Question 40

The goal of waiting-line management is to minimize:

A) the sum of customer waiting costs and capacity costs.
B) the sum of customer waiting time and service time.
C) capacity costs.
D) customer waiting time.
E) idle servers.

Question 41

A multiple-channel system has customers arriving at an average rate of five per hour and an average service time of 40 minutes. The minimum number of servers for this system to be underloaded is:

A) 2.
B) 3.
C) 4.
D) 5.
E) 6.

Question 42

When the waiting cost incurred likely varies based on some customer characteristic, an appropriate queuing model is:

A) single channel, single phase.
B) single channel, multiple phase.
C) multiple channel, single priority.
D) multiple channel, multiple phase.
E) multiple channel, multiple priority.

Question 43

A restaurant at a popular Colorado casino provides priority service to player's card holders. The restaurant has 10 tables or booths where customers may be seated. The service time (time a booth or table is occupied) averages 42 minutes once a party is seated. The customer arrival rate is 8 parties per hour, with the parties being equally divided between card holders and people without player's cards. What is the average time that player's card holders wait to be seated?

A) approx. 24 seconds
B) approx. 55 seconds
C) approx. 4 minutes
D) approx. 40 minutes
E) approx. 2 hours

Question 44

A restaurant at a popular Colorado casino provides priority service to player's card holders. The restaurant has 10 tables or booths where customers may be seated. The service time (time a booth or table is occupied) averages 42 minutes once a party is seated. The customer arrival rate is 8 parties per hour, with the parties being equally divided between card holders and people without player's cards. On average, how much longer do parties without player's cards spend in the system, compared to parties with the player's cards?

A) approx. 30 seconds
B) approx. 4 minutes
C) approx. 8 minutes
D) approx. 32 minutes
E) It is impossible to say without more information.

Question 45

A single-channel queuing 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:

A) increase utilization.
B) decrease utilization.
C) increase the average waiting time.
D) decrease the average waiting timE.
E) not have any effect since the service time is unchanged.

Question 46

If a firm has reached the point at which further reducing waiting time is not economically feasible, reducing the ______________ is sometimes attractive.

A) channels
B) perceived service time
C) capacity underload
D) perceived waiting time
E) system underutilization

Question 47

A ________ is one way of reducing perceived waiting time.

A) bonus
B) gatekeeper
C) reservation
D) diversion
E) number calling system

Question 48

A bank of 10 machines requires regular periodic service. Machine running time and service time are both exponential. Machines run for an average of 44 minutes between service requirements, and service time averages six minutes per machine. If operators cost $15 per hour in wages and fringe benefits and machine downtime costs $75 per hour in lost production, what is the optimal number of operators for this bank of machines?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 49

A bank of 10 machines requires regular periodic service. Machine running time and service time are both exponential. Machines run for an average of 44 minutes between service requirements, and service time averages six minutes per machine. What is the probability that a machine will have to wait for service with two operators?

A) .654
B) .090
C) .346
D) .910
E) .016

Question 50

Which one of the following measures of system performance is a key measure with respect to customer satisfaction?

A) average number of customers waiting in line
B) system utilization
C) average number of customers in the calling population
D) probability of a server being busy
E) capacity costs per hour

Question 51

An alternative strategy to increase the capacity of a service system is:

A) reducing the number of arrivals.
B) increasing variability.
C) increasing the processing ratE.
D) reducing the number of servers.
E) reducing the processing rate.

Question 52

A bank is designing a new branch office and needs to determine how much driveway space to allow for cars waiting for drive-up teller service. The drive-up service will have three tellers and a single waiting line. At another branch of the bank in a similar setting, the average service time for drive-up tellers is four minutes per customer, and average arrival rate is 36 customers per hour. It is expected that the new bank will have similar characteristics.
How many spaces should be provided to have a 96 percent probability of accommodating all of the waiting cars?

A) 10
B) 11
C) 12
D) 13
E) 14

Question 53

A single-phase queuing system in which each arriving customer will be served by a three-member crew has four crews with three members each. The number of "servers" is:

A) 3.
B) 4.
C) 7.
D) 12.
E) 1.

Question 54

A restaurant at a popular Colorado casino provides priority service to player's card holders. The restaurant has 10 tables or booths where customers may be seated. The service time (time a booth or table is occupied) averages 42 minutes once a party is seated. The customer arrival rate is 8 parties per hour, with the parties being equally divided between card holders and people without player's cards. On average, how many parties with player's cards are waiting to be seated?

A) 0.000
B) 0.027
C) 0.061
D) 2.827
E) 5.688

Question 55

A multiple-channel queuing system with a Poisson arrival rate and exponential service time has an average arrival rate of four customers per hour and an average service time of 18 minutes per customer. The minimum number of servers required to avoid an overloaded system is:

A) 1.
B) 2.
C) 3.
D) 4.
E) 5.

Question 56

A bank of 10 machines requires regular periodic service. Machine running time and service time are both exponential. Machines run for an average of 44 minutes between service requirements, and service time averages six minutes per machine. What is the average machine downtime with two operators?

A) 1.71 minutes
B) 3.46 minutes
C) 6.25 minutes
D) 7.71 minutes
E) 9.46 minutes

Question 57

A restaurant at a popular Colorado casino provides priority service to player's card holders. The restaurant has 10 tables or booths where customers may be seated. The service time (time a booth or table is occupied) averages 42 minutes once a party is seated. The customer arrival rate is 8 parties per hour, with the parties being equally divided between card holders and people without player's cards. What is the average time that parties without player's cards wait to be seated?

A) approx. 24 seconds
B) approx. 55 seconds
C) approx. 4 minutes
D) approx. 40 minutes
E) approx. 2 hours

Question 58

A single-bay car wash with a Poisson arrival rate and an exponential service time has cars arriving an average of 10 minutes apart, and an average service time of four minutes. The system utilization is:

A) .24.
B) .40.
C) .67.
D) 2.50.
E) 1.25.

Question 59

A bank of 10 machines requires regular periodic service. Machine running time and service time are both exponential. Machines run for an average of 44 minutes between service requirements, and service time averages six minutes per machine. What is the average number of machines down when there is one operator?

A) 1.49
B) 3.35
C) 4.40
D) 6.65
E) 8.51

Question 60

A restaurant at a popular Colorado casino provides priority service to player's card holders. The restaurant has 10 tables or booths where customers may be seated. The service time (time a booth or table is occupied) averages 42 minutes once a party is seated. The customer arrival rate is 8 parties per hour, with the parties being equally divided between card holders and people without player's cards. On average, how many parties without player's cards are waiting to be seated?

A) 0.000
B) 0.027
C) 0.061
D) 2.861
E) 5.688

Question 61

In a multichannel system with multiple waiting lines, customers shifting among the waiting lines is an example of:

A) departing.
B) utilizing.
C) abandoning.
D) balking.
E) jockeying.

Question 62

A restaurant that implements a limited menu and a "no substitutions" policy during peak dining hours is practicing _____________ with respect to waiting-line management.

A) demand shifting
B) queuing psychology
C) service standardization
D) service phasing
E) outsourcing

Question 63

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

A) demand shifting.
B) queuing psychology.
C) service phasing.
D) service standardization.
E) outsourcing.

Question 64

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

A) putting all clocks out of sight
B) removing couches
C) having the patient fill out forms
D) implementing a "no-cell-phone" policy
E) keeping expected waiting times from the patients