Deck 7: S Advanced Waiting Line Theory and Simulation Modeling

Question 1

All waiting line formulas assume that customers are served on a first-come first-served (FCFS)basis.

Answer 1

True

Question 2

A customer enters a business and joins the one line that snakes back and forth through the lobby in order to receive service.The initial part of the service is performed by one customer service representative,after which the customer enters a second,shorter line to complete the service before leaving the establishment.Which description of this waiting line system is appropriate?

A)single channel,single phase
B)single channel,multiple phase
C)multiple channel,single phase
D)multiple channel,multiple phase

Answer 2

B

Question 3

Monte Carlo simulation uses statistical sampling to create outcomes for a large number of trials.

Answer 3

True

Question 4

Customers enter the stadium and purchase refreshments before they are shown to their seats by experienced ushers.The concession stand lines are considered elements in the simulation model.

Question 5

The department chair is out of town at a conference and you,as the assistant department chair,find yourself besieged by dozens of students needing permission to get into a very popular (but closed)class.Student arrivals are governed by the Poisson distribution with a mean of 5 minutes.Telling the students that they can't get into the closed class takes about 3 minutes,and this average is exponentially distributed.About how long does it take a student to wait in line and receive your valuable service?

A)0)125 minutes
B)0)075 hours
C)4)5 minutes
D)7)5 minutes

Question 6

Customers enter the stadium and purchase refreshments before they are shown to their seats by experienced ushers.The customers are considered objects in the simulation model.

Question 7

The department chair is out of town at a conference and you,as the assistant department chair,find yourself besieged by dozens of students needing permission to get into a very popular (but closed)class.Student arrivals are governed by the Poisson distribution with a mean of 10 minutes.Telling the students that they can't get into the closed class takes about 3 minutes,and this average is exponentially distributed.About how many students are waiting outside your office door?

A)0)13 students
B)0)43 students
C)1)25 students
D)2)25 students

Question 8

In waiting line theory,the number of channels refers to the number of customer waiting lines in the system.

Question 9

The department chair is out of town at a conference and you,as the assistant department chair,find yourself besieged by dozens of students needing permission to get into a very popular (but closed)class.Student arrivals are governed by the Poisson distribution with a mean of 10 minutes.Telling the students that they can't get into the closed class takes about 5 minutes,and this average is exponentially distributed.About how long do students wait outside your office door?

A)0)083 minutes
B)0)083 hours
C)0)50 minutes
D)0)50 hours

Question 10

A waiting line cannot be both multiple-channel and multiple-phase.

Question 11

The Greek letter lambda (λ)is used to represent the service rate of a waiting line system.

Question 12

In most cases,simulation models provide optimal solutions to problems just like most of the equations presented in your textbook.

Question 13

A customer enters a business and has the opportunity to select any one of three lines to receive service.The service is performed by one customer service representative after which the customer leaves the establishment.Which description of this waiting line system is appropriate?

A)single channel,single phase
B)single channel,multiple phase
C)multiple channel,single phase
D)multiple channel,multiple phase

Question 14

The department chair is out of town at a conference and you,as the assistant department chair,find yourself besieged by dozens of students needing permission to get into a very popular (but closed)class.Student arrivals are governed by the Poisson distribution with a mean of 5 minutes.Telling the students that they can't get into the closed class takes about 3 minutes,and this average is exponentially distributed.About how many students are waiting outside your office door and in your office?

A)0)5
B)1)0
C)1)5
D)2)0

Question 15

With only a half hour for lunch I screamed into the parking lot of the nearest Golden Arches Supper Club at 40 miles an hour.When I saw the drive through line was 15 cars deep I didn't bother getting in line;I was off to visit the Colonel.This behavior might be described as balking.

Question 16

In most waiting line models,customers are assumed to arrive at random intervals,based on a normal distribution.

Question 17

It is more costly to create a more realistic simulation than one that is less realistic.

Question 18

Everything about two different waiting line systems is the same except one system has a constant service time and the other has a Poisson distributed service time.Customers using the system with the constant service time will have half the waiting time of the customers using the system with Poisson distributed service times.

Question 19

The term time compression refers to the phenomenon that a server tends to speed up the service process if the waiting line exceeds some critical number of customers.

Question 20

Customer arrivals at a dry cleaning service occur randomly throughout the day.The distribution that is usually used to model the interval between arrivals is the:

A)Poisson distribution.
B)uniform distribution.
C)random distribution.
D)normal distribution.

Question 21

On average,how many customers are waiting in line?

A)9
B)11
C)13
D)15

Question 22

Customers pass by any one of forty ticket takers on their way in the arena for a WWE event.This is a single ________ system.

Question 23

How long does a customer spend waiting for a haircut?

A)17 minutes
B)20 minutes
C)23 minutes
D)26 minutes

Question 24

A single channel single server system requires that the ________ rate be larger than the ________ rate.

Question 25

One assumption in most waiting line analyses is that the number of customers is ________.

Question 26

The bank manager of a busy downtown location found herself unable to find good teller help so she invested in an ATM to handle the routine withdrawals that tended to occupy an inordinate amount of the teller's time.Before she installed the ATM she found that customers were arriving on average every 60 seconds (Poisson distributed)and it took a teller 20 seconds (exponentially distributed)to process their request.The ATM is able to maintain a constant 30 second service time.What is the impact on the waiting time for the customers?

A)There is no change.
B)The wait in the ATM line is 50% shorter than the wait in the teller line.
C)The wait in the ATM line is 50% higher than the wait in the teller line.
D)The wait in the ATM line is 25% shorter than the teller line.

Question 27

One advantage of simulation modeling is:

A)it allows the user to conduct a "what if" analysis.
B)the many simplifying assumptions that are often made when using it.
C)the fact that an optimal solution is reached.
D)the time and cost required to make a perfectly realistic simulation.

Question 28

Management is concerned about the waiting time for customers and decides to train one more student.If the arrival and service rates remain the same as in the original scenario,what happens to the number of customers in the system?

A)There are about half as many as in the original scenario.
B)There are about a third as many as in the original scenario.
C)There are about a fourth as many as in the original scenario.
D)There are about a fifth as many as in the original scenario.

Question 29

Which of the following statements about simulation is BEST?

A)Tools like linear programming and regression analysis work best when they are simulated.
B)Simulation permits managers to test the effects of new policies and procedures without disrupting customer service.
C)As computers have increased in power,simulation results have become less accurate.
D)Computer-based simulation is the only "true" simulation.

Question 30

Many complex waiting line situations cannot be analyzed through neatly derived formulas;in these cases,________ is the best method of analysis.

Question 31

Each outcome of flipping a fair coin is completely independent of the previous flip.This outcome is known as:

A)simulation.
B)Monte Carlo.
C)50/50.
D)memoryless.

Question 32

Barber College is the best deal in town! For only $5,you can get a shampoo and cut by any one of four untrained stylists completed in 7.5 minutes on average.Perhaps this is why customers show up on average two minutes apart (both interarrival times and service times are exponentially distributed).
What percentage of the time are the four stylists working with customers?

A)94%
B)90%
C)84%
D)80%

Question 33

The effect of the Excel formula =20∗RAND()is that:

A)twenty entries of a random variable with a mean of zero will be created.
B)twenty entries of a random variable with a mean of one will be created.
C)one entry of a random variable with a mean of twenty will be created.
D)one entry of a random variable with a mean of ten will be created.

Question 34

Customers that leave the system after waiting in line for a while are ________,but customers that don't even join the line because it looks too long are ________.

Question 35

The bank manager of a busy downtown location found herself unable to find good teller help so she invested in an ATM to handle the routine withdrawals that tended to occupy an inordinate amount of the teller's time.Before she installed the ATM she found that customers were arriving on average every 2 minutes (Poisson distributed)and it took a teller 30 seconds (exponentially distributed)to process their request.The ATM is able to maintain a constant 30 second service time.What is the impact on the number of customers waiting in line?

A)There is no change.
B)The ATM line is half as long as the teller line.
C)The ATM line is twice as long as the teller line.
D)The ATM line is 25% shorter than the teller line.

Question 36

The only way to enter Jellystone Park is past Ranger Smith,who checks your camping gear and warns you about the bears in the park.The next step of the entrance process is to pay your site fee to Ranger Dwayne.This is a single ________ system.

Question 37

Just before he retired for the evening,Saba started his simulation program to simulate five years of hospital operations as he slept.His ability to generate five years of data overnight is a textbook example of ________.

Question 38

Which of the following is characteristic of Monte Carlo simulation?

A)Results are usually not valid,but provide managers with an approximation.
B)Time compression is not possible using this technique.
C)Statistical sampling is used to create outcomes for many trials.
D)Computer packages such as Simquick and Arena can show on-screen graphics of customers moving through the system or inventory accumulation.

Question 39

The bank manager of a busy downtown location found herself unable to find good teller help so she invested in an ATM to handle the routine withdrawals that tended to occupy an inordinate amount of the teller's time.Before she installed the ATM she found that customers were arriving on average every 2 minutes (Poisson distributed)and it took a teller 30 seconds (exponentially distributed)to process their request.The ATM is able to maintain a constant 30 second service time.What is the impact on system utilization?

A)There is no change.
B)Utilization has dropped by 15%.
C)Utilization has dropped by 30%.
D)Utilization has dropped by 45%.

Question 40

If 5 minutes pass between customer arrivals,then the ________ is 12 per hour.

Question 41

A process is ________ if the outcome of one trial does not have any impact on the next trial.

Question 42

Simulation permits the modeler to discover what might happen should certain events occur,for example,extreme levels of customer demand,equipment malfunction,etc.This type of analysis is known as ________ analysis.

Question 43

________ is an Excel function that generates a uniformly distributed random number between 0 and 1.

Question 44

Why would someone choose to use simulation to analyze a waiting line problem rather than use a formula? What are the advantages and disadvantages of a simulation approach?

Question 45

One approach to mathematical simulation that can be calculated in an Excel spreadsheet is ________.

Question 46

It's a beautiful sunny day after a week of rainy weather and both of the local car washes are busy.One car wash is fully automated,touchless,and can wash a vehicle of any size to a dazzling luster in 5 minutes flat.The other car wash is a fund raiser staffed by eager amateurs that work on one car at a time and can finish it in about 4 minutes (their time is governed by the Poisson distribution).Customer arrivals at both car washes are Poisson distributed with a mean of 10 per hour.How long does it take the average customer to work his way through either system? How many customers are in the systems on average?

Question 47

Gerard is choosing between two methods of organizing his bakery.Method one will require a counter person to wait on each customer individually before they proceed to the cashier to pay for their purchases.In this system,customers will arrive at the rate of 8 per hour and can be served by the counter person at the rate of 15 per hour.The cashier will be capable of serving customers at the rate of 20 per hour.For simplification purposes,assume that the arrival rate at the cashier phase is identical to the arrival rate at the first phase and that these waiting lines can be analyzed independently and combined.
Method two will have the two employees wait on customers as they select their pastries and also collect their money once their selections have been made.Customers still arrive at the rate of 8 per hour but now the total service time (pastry selection and payment collection)takes 5 minutes per customer.Calculate the average number of customers in the bakery and the average time spent in the bakery for both systems and make your recommendations to Gerard.

Question 48

Barber College is the best deal in town! For only $5,you can get a shampoo and cut by any one of four untrained stylists completed in 7.5 minutes on average.Perhaps this is why customers show up on average two minutes apart (both interarrival times and service times are exponentially distributed).
Develop a full description of the system performance.How much does performance improve if another barber is added to the customer service staff?

Question 49

What is Monte Carlo simulation and how is one conducted?