Deck 10: Waiting Line Analysis and Simulation

Question 1

The Poisson probability distribution is used in waiting line management when one is interested in the number of arrivals to a queue during some fixed time period.

Answer 1

True

Question 2

The demand on a hospital's emergency medical services is considered a controllable arrival pattern of the calling population.

Answer 2

False

Question 3

A constant arrival rate is more common in productive systems than a variable arrival rate.

Answer 3

False

Question 4

Arrival characteristics in a queuing problem analysis include the length of the queue.

Question 5

An infinite population in waiting line management refers to a population that is large enough in relation to the service system so that the change in population size caused by subtractions or additions to the population does not significantly affect the system probabilities.

Question 6

The admissions system in a hospital for patients is an example of a single-channel, single-phase queuing system.

Question 7

Gas stations, loading docks, and parking lots have infinite potential length of lines for their respective queuing systems.

Question 8

The demand on a hospital's emergency medical services is considered an uncontrollable arrival pattern of the calling population.

Question 9

The customer arrivals in a queuing system come almost exclusively from infinite populations.

Question 10

Highest-profit customer first is a queue discipline discussed in the textbook.

Question 11

The customer arrivals in a queuing system come almost exclusively from finite populations.

Question 12

A finite population in waiting line management refers to a population that is large enough in relation to the service system so that the change in population size caused by subtractions or additions to the population does not significantly affect the system probabilities.

Question 13

Longest waiting time in line is a queue discipline discussed in the textbook.

Question 14

Ideally, in waiting line or queuing analysis, we want to balance the cost of service capacity with the cost of waiting.

Question 15

A variable arrival rate is more common in waiting line management than a constant arrival rate.

Question 16

A tellers' window in a bank is an example of a single-channel, multiphase queuing system.

Question 17

A car wash is an example of a single-channel, multiphase queuing system.

Question 18

There are different queuing models to fit different queuing situations.

Question 19

Best customer last is a queue discipline discussed in the textbook.

Question 20

In a practical sense, an infinite queue is one that includes every possible member of the served population.

Question 21

In a department 25 machines are kept running by three operators who respond to randomly occurring equipment problems. An analyst who wanted to know how much production was being lost by machines waiting for service could use queuing theory analysis to find out.

Question 22

Balking and reneging mean the same thing.

Question 23

There is one major practical problem in using any queuing discipline: ensuring that customers know and follow the rule.

Question 24

While spreadsheets can be somewhat useful for a variety of simulation problems, they can be confusing and are vulnerable to several drawbacks, including weak routines for random-number selection.

Question 25

In a waiting line situation, multiple lines occur only when there are multiple servers.

Question 26

In a practical sense, a finite population is one that potentially would form a very long line in relation to the capacity of the serving system.

Question 27

Spreadsheet simulations have become obsolete due in part to specialized computer simulation languages like SLAM or SIMAN.

Question 28

Arrival patterns can be influenced or even controlled to a certain degree.

Question 29

A family arriving at a motel would be considered a batch arrival.

Question 30

Waiting line formulas generally specify service rate as the capacity of the server in number of units per time period.

Question 31

The spreadsheet function RAND() returns a number between negative and positive one.

Question 32

The rules of selection for a queue have a relatively minor impact on its overall performance.

Question 33

When service times are random, they can be approximated by the Poisson distribution.

Question 34

Simulation models can be classified as continuous or discrete.

Question 35

In a department 25 machines are kept running by three operators who respond to randomly occurring equipment problems. When an operator is not immediately available for servicing a machine having a problem, the amount of production being lost by machines waiting for service increases. An analyst can use queuing theory analysis to determine whether to pay overtime to get an operator from a different shift or not.

Question 36

A constant arrival distribution means that customers continue to arrive for the entire time the system is open.

Question 37

The term "queue discipline" involves the art of controlling surly and unruly customers who have become irritated by waiting.

Question 38

The spreadsheet function RANDBETWEEN() can return a number between any two numbers between positive and negative infinity.

Question 39

In a department, 25 machines are kept running by three operators who respond to randomly occurring equipment problems. An analyst wanting to know whether to add a fourth operator or downsize to two operators would be helped by using queuing theory analysis.

Question 40

Special-purpose simulation software is specially built to run specific applications and may have provisions in manufacturing models to allow for specifying the number of workcenters, their descriptions, arrival rates, and even batch sizes.

Question 41

Which of the following is not a suggestion for managing queues presented in the textbook?

A) Train your servers to be friendly.
B) Segment the customers.
C) Determine an acceptable waiting time for your customers.
D) Inform your customers of what to expect.
E) Encourage customers to come during slack periods.

Question 42

Which of the following is an example of a finite population in a queuing system?

A) People waiting to place their order at a fast-food restaurant
B) The departmental faculty in line at the copier
C) People waiting in line at an ATM
D) Patients seeking help in a hospital emergency room
E) Taxpayers calling for assistance from the IRS

Question 43

For an infinite queuing situation, if the arrival rate for loading trucks is 5 trucks per hour, what is the mean time between arrivals?

A) 5 hours
B) 2.5 hours
C) 0.2 hour
D) 0.1 hour
E) None of these choices are correct.

Question 44

Which of the following is not a suggestion for managing queues presented in the textbook?

A) Try to divert your customer's attention when waiting.
B) Segment the customers.
C) Encourage customers to come during the slack periods.
D) Train your people to be friendly.
E) Periodically close the service channel to temporarily disperse the line.

Question 45

A roller-coaster ride in an amusement park employs which type of queuing system line structure?

A) Single channel, single phase
B) Single channel, multiphase
C) Multichannel, single phase
D) Multichannel, multiphase
E) None of these choices are correct.

Question 46

Which of the following is not a queue discipline discussed in the textbook?

A) First come, first served
B) Last in, first out
C) Limited needs
D) Shortest processing time
E) Best customer first

Question 47

Which of the following are the three major components of a queuing system?

A) The source population, how customers exit the system, and the queuing discipline
B) The number of servers, the service speed, and the waiting line
C) The source population, how the customer exits the system, and the servicing system
D) The source population and the way customers arrive at the system, the serving systems, and how customers exit the system
E) The service speed, the queue discipline, and the waiting line

Question 48

Buying food at a large food store with multiple checkout counters features which type of queuing system line structure?

A) Single channel, single phase
B) Single channel, multiphase
C) Multichannel, single phase
D) Multichannel, multiphase
E) None of these choices are correct.

Question 49

Getting an autograph from a famous person might involve standing in which type of queuing line structure?

A) Single channel, single phase
B) Single channel, multiphase
C) Multichannel, single phase
D) Multichannel, multiphase
E) None of these choices are correct.

Question 50

Which of the following is a suggestion for managing queues that is mentioned in the textbook?

A) Put up a serpentine lane to keep people from jumping ahead in line.
B) Use humor to defuse a potentially irritating situation.
C) Segment the customers.
D) Assure customers that the wait is fair, and inform them of the queue discipline.
E) Tell people in the queue that each will be served as soon as possible.

Question 51

Which of the following is a suggestion for managing queues presented in the textbook?

A) Train your servers to be friendly.
B) Tell customers that the line should encourage them to come during slack periods.
C) Give each customer a number.
D) Periodically close the service channel to temporarily disperse the line.
E) Use humor to defuse a potentially irritating situation.

Question 52

Assume the service rate for a queue in a truck-loading operation is 2 trucks per hour. Using the infinite queuing notion for the models presented in the textbook, which of the following is the average service time?

A) 2 hours
B) 1 hour
C) 0.5 hour
D) 0.25 hour
E) None of these choices are correct.

Question 53

Standing in line to buy a ticket for a movie where there are multiple windows at which to buy tickets is which type of queuing system line structure?

A) Single channel, single phase
B) Single channel, multiphase
C) Multichannel, single phase
D) Multichannel, multiphase
E) None of these choices are correct.

Question 54

Machine breakdown and repair in a 12-machine factory having three repair mechanics would develop which type of queuing system line structure concerning machine breakdowns?

A) Single channel, single phase
B) Single channel, multiphase
C) Multichannel, single phase
D) Multichannel, multiphase
E) None of these choices are correct.

Question 55

Machine breakdown and repair in a 12-machine factory having one repair mechanic would develop which type of queuing system line structure concerning machine breakdowns?

A) Single channel, single phase
B) Single channel, multiphase
C) Multichannel, single phase
D) Multichannel, multiphase
E) None of these choices are correct.

Question 56

Which of the following is a suggestion for managing queues that is mentioned in the textbook?

A) Put up a serpentine lane to keep people from jumping ahead in line.
B) Use humor to defuse a potentially irritating situation.
C) Train your servers to be friendly.
D) Assure customers that the wait is fair, and inform them of the queue discipline.
E) Tell people in the queue that each will be served as soon as possible.

Question 57

Which of the following queue disciplines is discussed in the textbook?

A) Emergencies first
B) Garner-Whitten formula
C) Newest customer first
D) Patient customers last
E) None of these choices are correct.

Question 58

In a college registration process, several department heads have to approve an individual student's semester course load. What is the queuing system line structure?

A) Single channel, single phase
B) Single channel, multiphase
C) Multichannel, single phase
D) Multichannel, multiphase
E) None of these choices are correct.

Question 59

Buying a ticket for a college football game where there are multiple windows at which to buy the ticket features which type of queuing system line structure?

A) Single channel, single phase
B) Single channel, multiphase
C) Multichannel, single phase
D) Multichannel, multiphase
E) None of these choices are correct.

Question 60

In essence, a queuing system includes several major components. Which of the following is not one of them?

A) Source population
B) Servicing system
C) How the customer exits the system
D) The queue discipline
E) None of these choices are correct.

Question 61

Customers arrive at a common queue at the coffee station with two identical coffee machines in a busy mall at the rate of 48 per hour, following Poisson distribution. Each customer mixes his or her specialty coffee taking 2 minutes on an average following an exponential process. What is the expected number of customers in the system at this coffee station?

A) infinity
B) 2.844
C) 2.444
D) 4.444
E) 3

Question 62

A company is concerned about the number of customers who have to wait for service in its customer service department. Assume the rate at which customers are serviced is 12 per hour. Using the infinite queuing notion for the models presented in the textbook, which of the following is the mean time between arrivals?

A) 12 minutes
B) 6 minutes
C) 2 minutes
D) 1 minute
E) None of these choices are correct.

Question 63

In modeling a simulation, random numbers from 00 to 99 are assigned with the intervals determined from frequency distributions for each behavior occurrence. Assume there are two behaviors, A and B, out of 100 tallies. On Behavior A you record 45 tallies, and on Behavior B you record 55 tallies. Which of the following is a correct random-number interval for Behavior A?

A) 00 to 45
B) 00 to 44
C) 56 to 99
D) 55 to 100
E) 45 to 100

Question 64

What is the mean of the Poisson distribution?

A) λ
B) λ²
C) 1/λ
D) 1/λ²
E) λ!

Question 65

What is the variance of the exponential distribution?

A) λ
B) λ²
C) 1/λ
D) 1/λ²
E) λ!

Question 66

Assuming a 24 hour operation in a warehouse, and an arrival following Poisson distribution with mean rate of 36 per day and service (unloading using a single bay) following exponential with a rate of 48 trucks per day, answer the following question. What is the expected number of trucks in the system?

A) 2.25
B) 1.5
C) 2
D) 1
E) 3

Question 67

In modeling a simulation, random numbers from 00 to 99 are assigned with the intervals determined from frequency distributions for each behavior occurrence. Assume there are two behaviors, X and Y, out of 50 tallies. On Behavior X you record 20 tallies, and on Behavior Y you record 30 tallies. Which of the following is a correct random-number interval for Behavior X?

A) 00 to 19
B) 01 to 20
C) 00 to 39
D) 41 to 61
E) 45 to 100

Question 68

These types of impatient customers arrive, view the situation, join the waiting line, and then, after some period of time, depart. What is this called?

A) Quitters
B) Reversing
C) Reneging
D) Balking
E) Bolting

Question 69

This Excel function always returns a number between zero and one.

A) NORMAL(0,1)
B) RANDOM()
C) RANDBETWEEN()
D) RAND(0,1)
E) RAND()

Question 70

Assuming a 24 hour operation in a warehouse, and an arrival following Poisson distribution with mean rate of 36 per day and service (unloading using a single bay) following exponential distribution with a rate of 48 trucks per day, answer the following question. What is the expected waiting time in the system (in hours) for a typical truck?

A) 2 hours
B) 1 hour
C) 1.5 hours
D) 0.25 hour
E) 0.5 hour

Question 71

These types of impatient customers arrive, survey both the service facility and the length of the line, and then decide to leave. What is this called?

A) Quitters
B) Reversing
C) Reneging
D) Balking
E) Bolting

Question 72

This Excel function always returns a number between negative and positive five.

A) NORMAL(−5,5)
B) RANDOM(−5,5)
C) RANDBETWEEN(−5,5)
D) RAND(−5,5)
E) RAND()*5

Question 73

Customers arrive at a single self-serve coffee machine in a busy mall at the rate of 20 per hour, following Poisson distribution. Each customer takes exactly 90 seconds to get his or her coffee. What is the expected number of customers in queue at this coffee machine?

A) 1.0
B) 1.5
C) 0.5
D) 2.0
E) 3.0

Question 74

In modeling a simulation, random numbers from 00 to 99 are assigned with the intervals determined from frequency distributions for each behavior occurrence. Assume there are two behaviors, A and B, out of 50 tallies. On Behavior A you record 15 tallies, and on Behavior B you record 35 tallies. Which of the following is a correct random-number interval for Behavior A (Choose the most appropriate answer.).
I. 00 to 29
II. 00 to 14
III. 70 to 99
IV. 35 to 49

A) I
B) II
C) III
D) IV
E) I or III

Question 75

What is the variance of the Poisson distribution?

A) λ
B) λ²
C) 1/λ
D) 1/λ²
E) λ!

Question 76

A small vendor has either a good day of sales with an average of $1,000 or a bad day with an average of only $500 for the day. To simulate these outcomes, random numbers from 00 to 99 should be assigned with the intervals determined from the frequency distribution. If, during the last 100 days, the vendor had 27 good days and 73 bad days, which of the following is a correct random-number interval for a bad day?

A) 28 to 99
B) 27 to 73
C) 27 to 100
D) 27 to 99
E) 00 to 26

Question 77

What is the mean of the exponential distribution?

A) λ
B) λ²
C) 1/λ
D) 1/λ²
E) λ!