Question 1

LIFS (last-in,first-served)is a common queue discipline,most often seen where people,not objects,form the waiting line.

Accepted Answer

A) True 
 B)False

Question 2

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 3

Of the three types of queue discipline,only ________ is assumed by the four primary waiting line models.

Accepted Answer

FIFO or FIFS or firs

Question 4

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 5

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)Pn

Question 6

In queuing problems,which of the following probability distributions is typically used to describe the number of arrivals per unit of time?

Accepted Answer

A) binomial 
B) normal 
C) Poisson 
D) exponential 
E) lognormal 
A) binomial 
B) normal 
C) Poisson 
D) exponential 
E) lognormal

Question 7

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 8

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 9

In the M/M/1 waiting line model with an arrival rate of 2 per hour and a service rate of 6 per hour,the utilization factor for the system is approximately 0.333.

Accepted Answer

A) True 
 B)False

Question 10

A waiting line meeting the M/M/1 assumptions has an arrival rate of 4 per hour and a service rate of 12 per hour.What is the probability that the waiting line is empty?

Accepted Answer

Po = 1 - λ

Question 11

At the order fulfillment center of a major mail-order firm,customer orders,already packaged for shipment,arrive at the sorting machine to be sorted for loading onto the appropriate truck for the parcel's address.The arrival rate at the sorting machine is at the rate of 100 per hour following a Poisson distribution.The machine sorts at the constant rate of 150 per hour.
a.What is the utilization rate of the system?
b.What is the average number of packages waiting to be sorted?
c.What is the average number of packages in the sorting system?
d.How long must the average package wait until it gets sorted?
e.What would Lq and Wq be if the service rate were exponential,not constant?

Accepted Answer

(a)The utilization rate is = 100/150 = 0

Question 12

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 13

The sign at the bank that reads,"Wait here for the first available teller," suggests the use of a ________ waiting line system.

Accepted Answer

A) dynamic-server,single-phase 
B) random-server,single-phase 
C) single-server,multiphase 
D) multiple-server,single-phase 
E) multiple-server,multiphase 
A) dynamic-server,single-phase 
B) random-server,single-phase 
C) single-server,multiphase 
D) multiple-server,single-phase 
E) multiple-server,multiphase

Question 14

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

Accepted Answer

• The average time each customer or obje

Question 15

What costs are present in waiting line analysis? How do these costs vary with the level of service?

Accepted Answer

The costs are the cost of providing serv

Question 16

A waiting line meeting the M/M/1 assumptions has an arrival rate of 4 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

Ws = 1 / ( μ- λ)= 1 / (12 - 4)

Question 17

Which of the following is an example of a finite arrival population?

Accepted Answer

A) copy machines in a copying shop that break down 
B) students at a large university registering for classes 
C) shoppers arriving at a supermarket 
D) cars arriving at a suburban car wash 
E) all of the above 
A) copy machines in a copying shop that break down 
B) students at a large university registering for classes 
C) shoppers arriving at a supermarket 
D) cars arriving at a suburban car wash 
E) all of the above

Question 18

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

Accepted Answer

A) 2/3 
B) 1 
C) 1.5 
D) 2 
E) 6 
A) 2/3 
B) 1 
C) 1.5 
D) 2 
E) 6

Question 19

What are the components in a waiting-line system?

Accepted Answer

The components of a waiting-li

Question 20

A manufacturing plant is trying to determine how long the average line for a repair process will be.If 10 machines arrive each hour and must wait 6 minutes in the line,how long will the line be,on average?

Accepted Answer

Little's Law: X mach

Exam 25: Waiting-Line Models

LIFS (last-in,first-served)is a common queue discipline,most often seen where people,not objects,form the waiting line.

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

Of the three types of queue discipline,only ________ is assumed by the four primary waiting line models.

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

In queuing problems,which of the following probability distributions is typically used to describe the number of arrivals per unit of time?

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

In the M/M/1 waiting line model with an arrival rate of 2 per hour and a service rate of 6 per hour,the utilization factor for the system is approximately 0.333.

A waiting line meeting the M/M/1 assumptions has an arrival rate of 4 per hour and a service rate of 12 per hour.What is the probability that the waiting line is empty?

The sign at the bank that reads,"Wait here for the first available teller," suggests the use of a ________ waiting line system.

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

What costs are present in waiting line analysis? How do these costs vary with the level of service?

A waiting line meeting the M/M/1 assumptions has an arrival rate of 4 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 of the following is an example of a finite arrival population?

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

What are the components in a waiting-line system?

A manufacturing plant is trying to determine how long the average line for a repair process will be.If 10 machines arrive each hour and must wait 6 minutes in the line,how long will the line be,on average?

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