Question 1

Which of the following is a requirement for application of Little's Law to be valid?

Accepted Answer

A) arrival rates that follow the Poisson distribution 
B) FIFO queue discipline 
C) steady state conditions 
D) single-server system 
E) multiphase system 
A) arrival rates that follow the Poisson distribution 
B) FIFO queue discipline 
C) steady state conditions 
D) single-server system 
E) multiphase system C

Question 2

Provide an example of a limited or finite population for a queue.

Accepted Answer

Answers will vary,but the textbook provides copiers at a copying shop in terms of breakdowns and repair.

Question 3

A crew of mechanics at the Highway Department Garage repair vehicles that break down at an average of λ = 7.5 vehicles per day (approximately Poisson in nature).The mechanic crew can service an average of μ = 10 vehicles per day with a repair time distribution that approximates an exponential distribution.
a.What is the utilization rate for this service system?
b.What is the average time before the facility can return a breakdown to service?
c.How much of that time is spent waiting for service?
d.How many vehicles are likely to be in the system at any one time?

Accepted Answer

(a)Utilization is 7.5 / 10 = .75 or 75 percent; (b)W_s = 1 / (10 - 7.5)= 1 / 2.5 = 0.4 days; (c)W_q = 7.5 / [10(10 - 7.5)] = 0.3 days; (d)L_s = 7.5 / (10 - 7.5)= 7.5 / 2.5 = 3 units

Question 4

A single-phase waiting-line system meets the assumptions of constant service time or M/D/1.Units arrive at this system every 12 minutes on average.Service takes a constant 8 minutes.What is the average number in the system Ls in units?

Accepted Answer

A) 2.25 
B) 2.5 
C) 3.0 
D) 1.33 
E) 5.0 
A) 2.25 
B) 2.5 
C) 3.0 
D) 1.33 
E) 5.0

Question 5

Four of the most widely used waiting line models-M/M/1 or A,M/M/S or B,M/D/1 or C,and Limited population or D-all share which of the following three characteristics?

Accepted Answer

A) normal arrivals,FIFO discipline,and normal service times 
B) Poisson arrivals,FIFO discipline,and a single-service phase 
C) Poisson arrivals,FIFO discipline,and exponential service times 
D) Poisson arrivals,no queue discipline,and exponential service times 
E) Poisson arrivals,single-server,and FIFO discipline 
A) normal arrivals,FIFO discipline,and normal service times 
B) Poisson arrivals,FIFO discipline,and a single-service phase 
C) Poisson arrivals,FIFO discipline,and exponential service times 
D) Poisson arrivals,no queue discipline,and exponential service times 
E) Poisson arrivals,single-server,and FIFO discipline

Question 6

Balk and renege are elements of queue discipline.

Accepted Answer

A) True 
 B)False

Question 7

A finite population waiting line model has an average service time T of 100 minutes and an average time between service requirements U of 400 minutes.What is the service factor X?

Accepted Answer

A) 0.20 
B) 0.25 
C) 4 
D) 5 
E) 300 minutes 
A) 0.20 
B) 0.25 
C) 4 
D) 5 
E) 300 minutes

Question 8

A college registrar's office requires you to first visit with one of three advisors and then with one of two financial professionals.This system is best described as which of the following?

Accepted Answer

A) single-server,single-phase system 
B) single-server,multiphase system 
C) multiple-server,single-phase system 
D) multiple-server,multiphase system 
E) multiple-server,cross-phase system 
A) single-server,single-phase system 
B) single-server,multiphase system 
C) multiple-server,single-phase system 
D) multiple-server,multiphase system 
E) multiple-server,cross-phase system

Question 9

A single-phase waiting-line system meets the assumptions of constant service time or M/D/1.Units arrive at this system every 10 minutes on average.Service takes a constant 4 minutes.What is the average length of the queue Lq in units?

Accepted Answer

A) 0.4 
B) 0.133 
C) 4.167 
D) 4.583 
E) 6 
A) 0.4 
B) 0.133 
C) 4.167 
D) 4.583 
E) 6

Question 10

A crew of mechanics at the Highway Department garage repair vehicles that break down at an average of λ = 8 vehicles per day (approximately Poisson in nature).The mechanic crew can service an average of μ= 10 vehicles per day with a repair time distribution that approximates an exponential distribution.
a.What is the probability that the system is empty?
b.What is the probability that there is precisely one vehicle in the system?
c.What is the probability that there is more than one vehicle in the system?
d.What is the probability of 5 or more vehicles in the system?

Accepted Answer

(a)P₀ = 1 - 8/10 = 0.20; (b)P_n >

Question 11

Which part of a waiting line has characteristics that involve a statistical distribution?

Accepted Answer

A) arrivals or inputs 
B) the waiting line itself 
C) the service facility 
D) A and C 
E) A,B,and C 
A) arrivals or inputs 
B) the waiting line itself 
C) the service facility 
D) A and C 
E) A,B,and C

Question 12

Suppose that a service facility has an average line of 2 customers that must wait,on average,5 minutes for service.How many customers are arriving per hour?

Accepted Answer

Use Little's Law that 2 custom

Question 13

Which one of the following is NOT a characteristic of a Model B or M/M/S system?

Accepted Answer

A) unlimited population size 
B) single server 
C) exponential service time pattern 
D) single phase 
E) Poisson arrival rate pattern 
A) unlimited population size 
B) single server 
C) exponential service time pattern 
D) single phase 
E) Poisson arrival rate pattern

Question 14

A waiting line meeting the M/M/1 assumptions has an arrival rate of 10 per hour and a service rate of 12 per hour.What is the average time a unit spends in the system and the average time a unit spends waiting (in hours)?

Accepted Answer

W_s = 1 / (μ - λ)= 1 / (12 - 10)

Question 15

A large discount store and supermarket has a hair styling salon on its premises.The salon has several operators.Salon customers can shop in other parts of the store until their name is called for salon service,at which time the customer will be served by the next available stylist.This scenario provides an example of which of the following?

Accepted Answer

A) multiple-server,limited queue length 
B) single-server,multiphase,limited queue length 
C) multiple-server,unlimited queue length 
D) multiple single-server systems,limited queue length 
E) single-server,unlimited queue length 
A) multiple-server,limited queue length 
B) single-server,multiphase,limited queue length 
C) multiple-server,unlimited queue length 
D) multiple single-server systems,limited queue length 
E) single-server,unlimited queue length

Question 16

Which one of the following is NOT a characteristic of a Model C or M/D/1 system?

Accepted Answer

A) single server 
B) single phase 
C) Poisson arrival rate pattern 
D) exponential service time pattern 
E) unlimited population size 
A) single server 
B) single phase 
C) Poisson arrival rate pattern 
D) exponential service time pattern 
E) unlimited population size

Question 17

Which of the following is most likely to violate a FIFO queue?

Accepted Answer

A) supermarket with no express lanes 
B) car repair garage 
C) emergency room 
D) fast-food restaurant 
E) All of the above are equally likely to violate a FIFO queue. 
A) supermarket with no express lanes 
B) car repair garage 
C) emergency room 
D) fast-food restaurant 
E) All of the above are equally likely to violate a FIFO queue.

Question 18

Which of the following is most likely to be served in a last-in,first-served (LIFS)queue discipline?

Accepted Answer

A) customers checking out at a grocery store 
B) the in-basket on a manager's desk 
C) patients entering a hospital emergency room 
D) patrons waiting to be seated in a casual-dining restaurant 
E) customers waiting to see a bank teller 
A) customers checking out at a grocery store 
B) the in-basket on a manager's desk 
C) patients entering a hospital emergency room 
D) patrons waiting to be seated in a casual-dining restaurant 
E) customers waiting to see a bank teller

Question 19

The common measures of a queuing system's performance include:

Accepted Answer

A) probability that the service facility will be idle,average queue length,and probability that the waiting time will exceed a specified duration. 
B) average time each customer spends in the system,probability that the service system will be idle,and average time each customer spends in the queue. 
C) average queue length,maximum time a customer may spend in the queue,and the utilization factor for the system. 
D) average time each customer spends in the system,maximum queue length,and probability of a specific number of customers in the system. 
E) maximum queue length,maximum time a customer may spend in the queue,and average queue length. 
A) probability that the service facility will be idle,average queue length,and probability that the waiting time will exceed a specified duration. 
B) average time each customer spends in the system,probability that the service system will be idle,and average time each customer spends in the queue. 
C) average queue length,maximum time a customer may spend in the queue,and the utilization factor for the system. 
D) average time each customer spends in the system,maximum queue length,and probability of a specific number of customers in the system. 
E) maximum queue length,maximum time a customer may spend in the queue,and average queue length.

Question 20

Which of the following is NOT a measure of a queue's performance?

Accepted Answer

A) average time spent in the queue 
B) average queue length 
C) probability that the service facility will be idle 
D) utilization factor for the system 
E) All of the above are performance measures. 
A) average time spent in the queue 
B) average queue length 
C) probability that the service facility will be idle 
D) utilization factor for the system 
E) All of the above are performance measures.

Exam 25: Waiting-Line Models

Which of the following is a requirement for application of Little's Law to be valid?

Provide an example of a limited or finite population for a queue.

A single-phase waiting-line system meets the assumptions of constant service time or M/D/1.Units arrive at this system every 12 minutes on average.Service takes a constant 8 minutes.What is the average number in the system Ls in units?

Four of the most widely used waiting line models-M/M/1 or A,M/M/S or B,M/D/1 or C,and Limited population or D-all share which of the following three characteristics?

Balk and renege are elements of queue discipline.

A finite population waiting line model has an average service time T of 100 minutes and an average time between service requirements U of 400 minutes.What is the service factor X?

A college registrar's office requires you to first visit with one of three advisors and then with one of two financial professionals.This system is best described as which of the following?

A single-phase waiting-line system meets the assumptions of constant service time or M/D/1.Units arrive at this system every 10 minutes on average.Service takes a constant 4 minutes.What is the average length of the queue Lq in units?

Which part of a waiting line has characteristics that involve a statistical distribution?

Suppose that a service facility has an average line of 2 customers that must wait,on average,5 minutes for service.How many customers are arriving per hour?

Which one of the following is NOT a characteristic of a Model B or M/M/S system?

A waiting line meeting the M/M/1 assumptions has an arrival rate of 10 per hour and a service rate of 12 per hour.What is the average time a unit spends in the system and the average time a unit spends waiting (in hours)?

Which one of the following is NOT a characteristic of a Model C or M/D/1 system?

Which of the following is most likely to violate a FIFO queue?

Which of the following is most likely to be served in a last-in,first-served (LIFS)queue discipline?

The common measures of a queuing system's performance include:

Which of the following is NOT a measure of a queue's performance?

Operations and Productivity

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Forecasting

Design of Goods and Services

Managing Quality

Process Strategy

Location Strategies

Layout Strategies

Human Resources,job Design,and Work Measurement

Supply Chain Management

Inventory Management

Aggregate Planning and Sop

Material Requirements Planning Mrpand Erp

Short-Term Scheduling

Jit,tps,and Lean Operations

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Sustainability in the Supply Chain

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A single-phase waiting-line system meets the assumptions of constant service time or M/D/1.Units arrive at this system every 12 minutes on average.Service takes a constant 8 minutes.What is the average number in the system L_s in units?

A single-phase waiting-line system meets the assumptions of constant service time or M/D/1.Units arrive at this system every 10 minutes on average.Service takes a constant 4 minutes.What is the average length of the queue L_q in units?