Question 1

What are Ls and Lq,as used in waiting line terminology? Which is larger,Ls or Lq? Explain.

Accepted Answer

L_s is the average number of units in the

Question 2

A crew of mechanics at the Highway Department Garage repair vehicles that break down at an average of λ = 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 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 - 5/10 = 0.50; (b)P_n >

Question 3

The cost of waiting decreases as the service level increases.

Accepted Answer

A) True 
 B)False

Question 4

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 5

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 6

In the basic queuing model (M/M/1),what probability distribution describes arrival rates?

Accepted Answer

A) continuous 
B) normal 
C) negative exponential 
D) Poisson 
E) lognormal 
A) continuous 
B) normal 
C) negative exponential 
D) Poisson 
E) lognormal

Question 7

Which of the following is NOT a common queuing situation?

Accepted Answer

A) grocery shoppers being served by checkout clerks 
B) commuters slowing or stopping at toll plazas to pay highway tolls 
C) machinery waiting to be repaired or maintained 
D) parcel delivery truck following its computer-generated route 
E) patients in a health clinic waiting to see one of several doctors 
A) grocery shoppers being served by checkout clerks 
B) commuters slowing or stopping at toll plazas to pay highway tolls 
C) machinery waiting to be repaired or maintained 
D) parcel delivery truck following its computer-generated route 
E) patients in a health clinic waiting to see one of several doctors

Question 8

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 9

A queuing model that follows the M/M/1 assumptions has λ = 2 and μ = 8.The average number in the system Ls is ________ and the utilization of the system is ________.

Accepted Answer

A) 3;100 percent 
B) 0.33;25 percent 
C) 4;33 percent 
D) 6;25 percent 
E) 4;25 percent 
A) 3;100 percent 
B) 0.33;25 percent 
C) 4;33 percent 
D) 6;25 percent 
E) 4;25 percent

Question 10

The greater the margin by which the arrival rate exceeds the service rate,the better the performance of the waiting line.

Accepted Answer

A) True 
 B)False

Question 11

Suppose that 1 customer arrives each minute in a Poisson distribution.Is it more likely that 2 customers or 0 customers will arrive each minute?

Accepted Answer

P(0)= e^(-1)(1^0)/0! = .368
P(

Question 12

Waiting-line models are useful to operations in such diverse settings as service systems,maintenance activities,and shop-floor control.

Accepted Answer

A) True 
 B)False

Question 13

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 14

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 15

A waiting line meeting the assumptions of M/M/1 has an average time between arrivals of 20 minutes,and it services items in an average of 10 minutes each.What is the utilization factor?

Accepted Answer

A) 0.25 
B) 0.33 
C) 0.50 
D) 0.67 
E) 3.00 
A) 0.25 
B) 0.33 
C) 0.50 
D) 0.67 
E) 3.00

Question 16

A finite population waiting line model with a single server has an average service time T of 200 minutes and an average time between service requirements U of 300 minutes.Calculate the service factor X.If the population consists of 5 elements,what are the average number waiting,the average number being serviced,and the average number running? Refer to Table D.8.

Accepted Answer

The service factor is X = T / (T + U)= 2

Question 17

In queuing problems,which of the following probability distributions is typically used to describe the time to perform the service?

Accepted Answer

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

Question 18

In the basic queuing model (M/M/1),what probability distribution describes service times?

Accepted Answer

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

Question 19

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 20

The ________ probability distribution is a continuous probability distribution often used to describe the service time in a queuing system.

Accepted Answer

negative e

Exam 25: Waiting-Line Models

What are Ls and Lq,as used in waiting line terminology? Which is larger,Ls or Lq? Explain.

The cost of waiting decreases as the service level increases.

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

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

In the basic queuing model (M/M/1),what probability distribution describes arrival rates?

Which of the following is NOT a common queuing situation?

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 = 8.The average number in the system Ls is ________ and the utilization of the system is ________.

The greater the margin by which the arrival rate exceeds the service rate,the better the performance of the waiting line.

Suppose that 1 customer arrives each minute in a Poisson distribution.Is it more likely that 2 customers or 0 customers will arrive each minute?

Waiting-line models are useful to operations in such diverse settings as service systems,maintenance activities,and shop-floor control.

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

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 assumptions of M/M/1 has an average time between arrivals of 20 minutes,and it services items in an average of 10 minutes each.What is the utilization factor?

In queuing problems,which of the following probability distributions is typically used to describe the time to perform the service?

In the basic queuing model (M/M/1),what probability distribution describes service times?

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

The ________ probability distribution is a continuous probability distribution often used to describe the service time in a queuing system.

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What are L_s and L_q,as used in waiting line terminology? Which is larger,L_s or L_q? Explain.

A queuing model that follows the M/M/1 assumptions has λ = 2 and μ = 8.The average number in the system L_s is and the utilization of the system is .