Question 1

An airline ticket counter,with several agents for one line of customers,is an example of 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) cross-server,single-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) cross-server,single-phase system

Question 2

A queuing model that follows the M/M/1 assumptions has λ = 3 and μ = 2.What is the average number of units in the system?

Accepted Answer

A) -3 
B) 3 
C) 0.667 
D) 150 percent 
E) Growing without limit,since λ is larger than μ. 
A) -3 
B) 3 
C) 0.667 
D) 150 percent 
E) Growing without limit,since λ is larger than μ.

Question 3

Which of the following represents a customer that reneged due to the waiting line?

Accepted Answer

A) A husband and wife decide to eat out instead after seeing the movie ticket line. 
B) A car drives past the first fast-food restaurant on Hamburger Row because the drive-through was full. 
C) A Black Friday shopper skipped one store because the line went around the building. 
D) A student ordered pizza online because the phone line was busy. 
E) A customer at a gas station went inside to buy a soda,but after waiting in line for a minute left the soda behind and went outside empty-handed. 
A) A husband and wife decide to eat out instead after seeing the movie ticket line. 
B) A car drives past the first fast-food restaurant on Hamburger Row because the drive-through was full. 
C) A Black Friday shopper skipped one store because the line went around the building. 
D) A student ordered pizza online because the phone line was busy. 
E) A customer at a gas station went inside to buy a soda,but after waiting in line for a minute left the soda behind and went outside empty-handed.

Question 4

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; the service factor X is 0.25.

Accepted Answer

A) True 
 B)False

Question 5

A dental clinic at which only one dentist works is open only two days a week.During those two days,patients arrive at the rate of three per hour.The doctor serves patients at the rate of one every 15 minutes.
a.What is the probability that the clinic is empty (except for the dentist and staff)?
b.What percentage of the time is the dentist busy?
c.What is the average number of patients in the waiting room?
d.What is the average time a patient spends in the office (wait plus service)?
e.What is the average time a patient waits for service?

Accepted Answer

(a)Po = 1 - 3/4 = 0.25; (b)The dentist i

Question 6

Suppose that a fast food restaurant wants the average line to be 4 customers and that 80 customers arrive each hour.How many minutes will the average customer be forced to wait in line?

Accepted Answer

Little's Law: 4 customers = (8

Question 7

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 three characteristics: Poisson arrivals,FIFO discipline,and exponential service times.

Accepted Answer

A) True 
 B)False

Question 8

In the analysis of queuing models,the Poisson distribution often describes arrival rates,while service times are often described by the negative exponential distribution.

Accepted Answer

A) True 
 B)False

Question 9

A(n)________ is a discrete probability distribution that often describes the arrival rate in queuing theory.

Accepted Answer

Poisson di

Question 10

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 = .

Question 11

Service times in an automobile repair shop tend to follow which probability distribution?

Accepted Answer

A) exponential 
B) normal 
C) triangular 
D) binomial 
E) Erlang 
A) exponential 
B) normal 
C) triangular 
D) binomial 
E) Erlang

Question 12

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 13

In queuing problems,the term "renege" refers to the fact that some customers leave the queue before service is completed.

Accepted Answer

A) True 
 B)False

Question 14

The source population is considered to be either ________ in its size.

Accepted Answer

A) finite or infinite 
B) fixed or variable 
C) known or unknown 
D) random or scheduled 
E) small or large 
A) finite or infinite 
B) fixed or variable 
C) known or unknown 
D) random or scheduled 
E) small or large

Question 15

A waiting-line system with one waiting line and three sequential processing stages is a multiple-server,single-phase system.

Accepted Answer

A) True 
 B)False

Question 16

A waiting-line system that meets the assumptions of M/M/S has λ = 5,μ = 4,and M = 2.For these values,Po is approximately 0.23077,and Ls is approximately 2.05128.What is the average time a unit spends in this system?

Accepted Answer

A) approximately 0.1603 
B) approximately 0.2083 
C) approximately 0.4103 
D) approximately 0.8013 
E) Cannot be calculated because λ is larger than μ. 
A) approximately 0.1603 
B) approximately 0.2083 
C) approximately 0.4103 
D) approximately 0.8013 
E) Cannot be calculated because λ is larger than μ.

Question 17

You have seen that,in an M/D/1 problem,the average queue length is exactly one-half the average queue length of an otherwise identical M/M/1 problem.Are all other performance statistics one-half as large also? Explain.

Accepted Answer

Only the average queue length

Question 18

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 19

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 20

Identify the seven major measures of a queue system's performance.

Accepted Answer

• The average time each customer or obje

Exam 25: Waiting-Line Models

An airline ticket counter,with several agents for one line of customers,is an example of which of the following?

A queuing model that follows the M/M/1 assumptions has λ = 3 and μ = 2.What is the average number of units in the system?

Which of the following represents a customer that reneged due to the waiting line?

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; the service factor X is 0.25.

Suppose that a fast food restaurant wants the average line to be 4 customers and that 80 customers arrive each hour.How many minutes will the average customer be forced to wait in line?

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 three characteristics: Poisson arrivals,FIFO discipline,and exponential service times.

In the analysis of queuing models,the Poisson distribution often describes arrival rates,while service times are often described by the negative exponential distribution.

A(n)________ is a discrete probability distribution that often describes the arrival rate in queuing theory.

Service times in an automobile repair shop tend to follow which probability distribution?

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

In queuing problems,the term "renege" refers to the fact that some customers leave the queue before service is completed.

The source population is considered to be either ________ in its size.

A waiting-line system with one waiting line and three sequential processing stages is a multiple-server,single-phase system.

A waiting-line system that meets the assumptions of M/M/S has λ = 5,μ = 4,and M = 2.For these values,Po is approximately 0.23077,and Ls is approximately 2.05128.What is the average time a unit spends in this system?

You have seen that,in an M/D/1 problem,the average queue length is exactly one-half the average queue length of an otherwise identical M/M/1 problem.Are all other performance statistics one-half as large also? Explain.

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?

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?

Identify the seven major measures of a queue system's performance.

Operations and Productivity

Operations Strategy in a Global Environment

Project Management

Forecasting

Design of Goods and Services

Managing Quality

Process Strategy

Capacity and Constraint Management

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

Maintenance and Reliability

Sustainability in the Supply Chain

Statistical Process Control

Supply Chain Management Analytics

Decision-Making Tools

Linear Programming

Transportation Models

Learning Curves

Simulation

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