Test-Bank-for-Heizer-Operations-Management-9e

MODULE F: SIMULATION

TRUE/FALSE

1.Simulation has numerous applications in modern business, but few of these are in the area of operations.

False (Introduction, easy)

2.All forms of simulation are based on probability or chance.

False (Introduction, easy)

3.The idea behind simulation is threefold: (1) to imitate a real-world situation mathematically, (2) then to study its properties and operating characteristics, and (3) finally to draw conclusions and make action decisions based on the results of the simulation.

True (What is simulation?, easy)

4.Simulation is usually capable of producing a more appropriate answer to a complex problem than can be obtained from a mathematical model.

True (What is simulation? moderate)

5.Virtually all large-scale simulations take place on computers, but small simulations can be conducted by hand.

True (What is simulation? easy) {AACSB: Use of IT}

6.One effective use of simulation is to study problems for which the mathematical models of operations management are not realistic enough.

True (Advantages and disadvantages of simulation, moderate)

7.Simulation allows managers to test the effects of major policy decisions on real-life systems without disturbing the real system.

True (Advantages and disadvantages of simulation, moderate)

8.Simulation provides optimal solutions to problems.

False (Advantages and disadvantages of simulation, moderate)

9.Like mathematical and analytical models, simulation is restricted to using the standard probability distributions.

False (Advantages and disadvantages of simulation, moderate)

10.Simulation models are inexpensive to design and use.

False (Advantages and disadvantages of simulation, moderate)

11.Simulation models, because they are based on the generation of random numbers, fail to give the same solution in repeated use to any particular problem.

True (Advantages and disadvantages of simulation, moderate)

12.By starting random number intervals at 01, not 00, the top of each range is the cumulative probability.

True (Monte Carlo simulation, moderate)

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13.A simulation model is designed to arrive at a single specific numerical answer to a given problem.

False (Advantages and disadvantages of simulation, moderate)

14.A simulation is "Monte Carlo" when the elements of a system being simulated exhibit chance in their behavior.

True (Monte Carlo simulation, moderate)

15.Random number intervals are based on cumulative probability distributions.

True (Monte Carlo simulation, moderate)

16.Simulation is the attempt to duplicate the features, appearance, and characteristics of a real system, usually via a computerized model.

True (What is simulation?, easy)

17.Results of simulation experiments with large numbers of trials or long experimental runs will generally be better than those with fewer trials or shorter experimental runs.

True (Monte Carlo simulation, moderate)

18.Some reasons for the use of simulation in queuing are that the four standard queuing models do not allow for LIFO (or LIFS) discipline, for multi-phase waiting lines, or for unusual arrival and service distributions.

True (Simulation of a queuing problem, easy)

19.In most real-world inventory problems, lead time and demand vary in ways that make simulation a necessity because mathematical modeling is extremely difficult.

True (Simulation and inventory analysis, easy)

20.One reason for using simulation rather than an analytical model in an inventory problem is that the simulation is able to handle probabilistic demand and lead times.

True (Simulation and inventory analysis, moderate)

21.The Las Vegas method is a simulation technique that uses random elements when chance exists in their behavior.

False (Monte Carlo simulation, easy)

22.Simulation can use any probability distribution that the user defines.

True (Advantages and disadvantages of simulation, moderate)

MULTIPLE CHOICE

23.Which of the following statements regarding simulation is true?

a.Simulation can be physical or mathematical.

b.Simulation has numerous areas of application in operations.

c.Simulation attempts to duplicate a real system.

d.Monte Carlo simulation is a chance-based mathematical model of a real system.

e.All of these are true.

e (What is simulation?, moderate)

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24.Which of the following is not an application of simulation in the area of operations?

a.personnel scheduling

b.truck dispatching

c.plant (or facility) layout

d.inventory management using EOQ principles

e.inventory planning and control

d (What is simulation?, moderate)

25.The seven steps in the use of simulation include all but which of the following?

a.Define the problem.

b.Construct a mathematical model.

c.Introduce important variable associated with the problem.

d.Find the optimal solution.

e.Run the experiment.

d (What is simulation?, moderate)

26.Which of the following is true regarding simulation?

a.Small problems can be done by hand.

b.Most simulations are computerized.

c.Real-world complications can be included in simulation models.

d.Simulation is most suitable where standard analytical models are too complex.

e.All of the above are true.

e (Advantages and disadvantages of simulation, moderate) {AACSB: Use of IT}

27.Which of the following is true regarding simulation?

a.If an analytical model can't solve a problem, neither can a simulation.

b.Simulation can only be done by computer.

c.Monte Carlo simulation requires the use of random numbers.

d.Simulation models are inexpensive.

e.All of the above are true.

c (Advantages and disadvantages of simulation, moderate)

28.Which of the following is true regarding the use of simulation?

a.It is always very easy to build a simulation model.

b.It is very inexpensive to use a simulation model.

c.It always yields optimum solutions.

d.It allows time-compression in testing major policy decisions.

e.Few constraints, if any, have to be considered.

d (Advantages and disadvantages of simulation, moderate)

29.Simulation is used for several reasons, including

a.MODEL development is a fast process

b.it is inexpensive

c.the models are usually simple

d.it can handle large and complex real-world problems

e.it always generates optimal solutions

d (Advantages and disadvantages of simulation, moderate)

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30.One of the advantages of simulation is that

a.it is much less expensive than a mathematical solution

b.it always generates a more accurate solution than a mathematical solution

c.the policy changes may be tried out without disturbing the real-life system

d.model development is less time consuming than for mathematical models

e.model solutions are transferable to a wide variety of problems

c (Advantages and disadvantages of simulation, moderate)

31.One of the disadvantages of simulation is that it

a.does not allow for very complex problem solutions

b.is not very flexible

c.is a trial-and-error approach that may produce different solutions in different runs

d.is very limited in the type of probability distribution that can be used

e.interferes with the production systems while the program is being run

c (Advantages and disadvantages of simulation, moderate)

32."Time compression" and the ability to pose "what-if" questions are elements of

a.Monte Carlo analysis

b.the disadvantages of simulation

c.physical simulations but not mathematical simulations

d.the advantages of simulation

e.the broad threefold idea of simulation

d (Advantages and disadvantages of simulation, moderate)

33.Setting up a probability distribution, building a cumulative probability distribution, and generating random numbers are

a.necessary when the underlying probability distribution is normal

b.three of the five steps in Monte Carlo analysis

c.elements of physical simulation but not mathematical simulation

d.the three steps involved in simulating a queuing problem

e.advantages of simulation

c (Monte Carlo simulation, moderate)

34.From a portion of a probability distribution, you read that P(demand = 0) is 0.05 and P(demand = 1) is 0.10. The cumulative probability for demand ≤ 1 would be

a.0.05

b.0.075

c.0.10

d.0.15

e.cannot be determined

d (Monte Carlo simulation, moderate) {AACSB: Analytic Skills}

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35.From a portion of a probability distribution, you read that P(demand = 1) is 0.05, P(demand = 2) is 0.15, and P(demand = 3) is .20. The cumulative probability for demand ≤ 3 would be

a.0.133

b.0.200

c.0.400

d.0.600

e.cannot be determined from the information given

e (Monte Carlo simulation, moderate) {AACSB: Analytic Skills}

36.From a portion of a probability distribution, you read that P(demand = 0) is 0.05, P(demand = 1) is 0.10, and P(demand = 2) is 0.20. The two-digit random number intervals for this distribution beginning with 01 are

a.01 through 05, 01 through 10, and 01 through 20

b.00 through 04, 05 through 14, and 15 through 34

c.01 through 05, 06 through 15, and 16 through 35

d.00 through 04, 00 through 09, and 00 through 19

e.01 through 06, 07 through 16, and 17 through 36

c (Monte Carlo simulation, moderate) {AACSB: Analytic Skills}

37.From a portion of a probability distribution, you read that P(demand = 0) is 0.25, and P(demand = 1) is 0.30. The random number intervals for this distribution beginning with 01 are

a.01 through 25, and 26 through 30

b.01 through 25, and 01 through 30

c.01 through 25, and 26 through 55

d.00 through 25, and 26 through 55

e.00 through 25, and 26 through 30

c (Monte Carlo simulation, moderate) {AACSB: Analytic Skills}

38.A distribution of service times at a waiting line indicates that service takes 6 minutes 30 percent of the time, 7 minutes 40 percent of the time, 8 minutes 20 percent of the time, and 9 minutes 10 percent of the time. In preparing this distribution for Monte Carlo analysis, the service time 8 minutes would be represented by the random number range

a.20 through 40

b.21 through 40

c.70 through 90

d.71 through 90

e.none of these

d (Monte Carlo simulation, moderate) {AACSB: Analytic Skills}

39.A distribution of service times at a waiting line shows that service takes 6 minutes 30 percent of the time, 7 minutes 40 percent of the time, 8 minutes 20 percent of the time, and 9 minutes 10 percent of the time. This distribution has been prepared for Monte Carlo analysis. The first two random numbers drawn are 53 and 74. The simulated service times are ____ minutes, then ____ minutes.

a.6; 7

b.7; 7

c.7; 8

d.8; 9

e.cannot determine, because no service time probability is that large

c (Monte Carlo simulation, moderate) {AACSB: Analytic Skills}

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40.A distribution of service times at a waiting line indicates that service takes 12 minutes 30 percent of the time and 14 minutes 70 percent of the time. In preparing this distribution for Monte Carlo analysis, the service time 13 minutes would be represented by the random number range

a.00 through 29

b.01 through 30

c.30 through 99

d.31 through 00

e.none of these; 13 minutes is not a possible outcome

e (Monte Carlo simulation, moderate) {AACSB: Analytic Skills}

41.A distribution of service times at a waiting line indicates that service takes 12 minutes 30 percent of the time and 14 minutes 70 percent of the time. This distribution has been prepared for Monte Carlo analysis. The first four random numbers drawn are 07, 60, 77, and 49. The average service time of this simulation is

a.12 minutes

b.13 minutes

c.13.5 minutes

d.14 minutes

e.none of these

c (Monte Carlo simulation, moderate) {AACSB: Analytic Skills}

42.A distribution of lead times in an inventory problem indicates that lead time was 1 day 20 percent of the time, 2 days 30 percent of the time, 3 days 30 percent of the time, and. 4 days 20 percent of the time. This distribution has been prepared for Monte Carlo analysis. The first four random numbers drawn are 06, 63, 57, and 02. The average lead time of this simulation is

a.1.75 days

b.2 days

c.3 days

d.3.5 days

e.none of these

b (Monte Carlo simulation, moderate) {AACSB: Analytic Skills}

43.The effects of OM policies over many months or years can be obtained by computer simulation in a short time. This phenomenon is referred to as

a.time suppression

b.time suspension

c.time compression

d.time inversion

e.time conversion

c (Advantages and disadvantages of simulation, moderate) {AACSB: Use of IT}

44.One of the disadvantages of simulation is that it

a.does not allow for very complex problem solutions

b.is not very flexible

c.may be very expensive and time-consuming to develop

d.is very limited in the type of probability distribution that can be used

e.interferes with the production systems while the program is being run

c(Advantages and disadvantages of simulation, moderate)

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45.One of the disadvantages of simulation is that it

a.does not allow for very complex problem solutions

b.produces solutions and inferences that are not usually transferable to other problems

c.cannot study the interactive effects of individual components or variables

d.is very limited in the type of probability distribution that can be used

e.interferes with the production systems while the program is being run

b (Advantages and disadvantages of simulation, moderate)

46.One of the advantages of simulation is that

a.it is much less expensive than a mathematical solution

b.it always generates a more accurate solution than a mathematical solution

c.it can study the interactive effects of individual components or variables

d.model development is less time consuming than for mathematical models

e.model solutions are transferable to a wide variety of problems

c (Advantages and disadvantages of simulation, moderate)

47.One of the advantages of simulation is that

a.real-world complications can be included that most OM models cannot permit

b.it always generates a more accurate solution than a mathematical solution

c.it is a trial-and-error approach that may produce different solutions in repeated runs

d.model development is less time consuming than for mathematical models

e.model solutions are transferable to a wide variety of problems

a (Advantages and disadvantages of simulation, moderate)

FILL-IN-THE-BLANK

48._____________ is the attempt to duplicate the features, appearance, and characteristics of a real system, usually via a computerized model.

Simulation (What is simulation? easy) {AACSB: Use of IT}

49.The _____________ method is a simulation technique that uses random elements when chance exists in their behavior.

Monte Carlo (What is simulation? moderate)

50.A(n) _____________________ is the accumulation of individual probabilities of a distribution. cumulative probability distribution (Monte Carlo simulation, moderate)

51.A(n) _______________ is a series of digits that have been selected by a totally random process. random number (Monte Carlo simulation, moderate)

52.The effects of OM policies over many months or years can be obtained by computer simulation in a short time. This phenomenon is referred to as _______________ .

time compression (Advantages and disadvantages of simulation, moderate) {AACSB: Use of IT}

53.The numbers used to represent each possible value or outcome in a computer simulation are referred to as _______________ .

random-number intervals (Monte Carlo simulation, moderate) {AACSB: Use of IT}

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SHORT ANSWERS

54.Would you simulate a problem for which there is an exact mathematical model already?

In terms of getting the problem solved, the mathematical model would be preferred. The problem would have an exact or optimal answer calculated by the mathematical model. Simulating this problem would introduce variability in the form of simulation results that differ with each run. However, there might be some gain in understanding from simulating a problem that is already well modeled. Such simulation might be of benefit in debugging a simulation program. (Advantages and disadvantages of simulation, moderate) {AACSB: Reflective Thinking}

55.Define simulation.

Simulation is the attempt to duplicate the features, appearance, and characteristics of a real system, usually via a computerized model. (Introduction, easy) {AACSB: Use of IT}

56.Identify five applications of simulation.

The five applications of simulation can be picked from a list in Table F.1. Some highlights are traffic-light timing, bus scheduling, plant layout, production scheduling, inventory planning, and waiting line analysis. (Introduction, easy)

57.State the three-fold idea behind simulation.

The three-fold idea behind simulation is to imitate a real-world situation mathematically; then to study its properties and operating characteristics; and finally to draw conclusions and make action decisions based on the results of the simulation. (What is simulation? moderate)

58.Identify the seven steps involved in using simulation.

1.Define the problem.

2.Introduce the important variables.

3.Construct the numerical model.

4.Set up possible courses of action.

5.Run the experiment.

6.Consider the results (perhaps modifying the model).

7.Decide what course of action to take.

(What is simulation?, easy)

59.What is the Monte Carlo method?

The Monte Carlo method is a simulation technique that uses random elements when chance exists in their behavior. (Monte Carlo simulation, easy)

60.Identify, in order, the five steps required to implement the Monte Carlo simulation technique.

The steps of the Monte Carlo simulation technique are: set up a probability distribution for important variables; build a cumulative probability distribution for each of these variables; establish an interval of random numbers for each variable; generate sets of random numbers; and actually simulate a set of trials. (Monte Carlo simulation, moderate)

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61.Explain how Monte Carlo simulation uses random numbers.

First, a cumulative probability distribution is set up for the element being modeled. From this, a set of random number intervals is established. A random number is generated and matched against the set of intervals. The random number will fall into only one interval, and that determines the value for the element being modeled. (Monte Carlo simulation, moderate)

62.What are the advantages and disadvantages of simulation models?

Advantages:

•Simulation is relatively straightforward and flexible.

•It can be used to analyze large and complex real-world situations that cannot be solved by closed-form operations management models.

•Simulation allows for inclusion of real-world complications that most OM models cannot permit.

•“Time compression” is possible with simulation.

•Simulation allows “What if __?” type questions.

•Simulations do not interfere with the real-world system under study.

•Simulation allows us to study the interactive effect of individual components or variables in order to determine which ones are important.

Disadvantages:

•Good simulation models are very expensive.

•Simulation does not generate optimal solutions.

•Managers must generate all the conditions and constraints for the solutions that they want to examine.

•Each simulation model is unique. Its solutions and inferences are not usually transferable

to other problems.

(Advantages and disadvantages of simulation, moderate)

63.Provide a small example illustrating how random numbers are used in Monte Carlo simulation.

For example, demand can be 0, 40% of the time, or 1, 60% of the time. The cumulative distribution is demand = 0, 0.40, and demand = 1, 1.00. The random number intervals are 01 through 40 for demand = 0 and 41 through 00 for demand = 1. A random number of 36 indicates demand = 0. Examples will vary. (Monte Carlo simulation, moderate) {Reflective Thinking}

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64.A waiting-line problem that cannot be modeled by standard distributions has been simulated. The table below shows the result of a Monte Carlo simulation. (Assume that the simulation began at 8:00 a.m. and there is only one server.) Why do you think this problem does not fit the standard distribution for waiting lines? Explain briefly how a Monte Carlo simulation might work where analytical models cannot.

Service times do not appear to be exponential. Rather, they seem to be extreme—very short or very long. Simulation can handle this with a cumulative probability distribution and a set of random number intervals. The Monte Carlo simulation will, with a large enough number of trials, mimic the reality of this system. (Monte Carlo simulation, difficult) {AACSB:

Reflective Thinking}

65.Explain what is meant by "simulation is not limited to using the standard probability distributions."

"Standard models" include normal, binomial, beta, uniform, Poisson, exponential, and other probability distributions. Each has a specific set of assumptions and parameters. Real-world (empirical) systems can have any distribution imaginable. Simulation can mimic these realworld distributions by use of random number intervals based on real-world behavior, and can therefore generate more realistic models than would occur if a standard model were used in place of a system-specific one. (Monte Carlo simulation, moderate)

66.Explain what is meant by the concept of “time compression” in simulation modeling.

The effects of OM policies over many months or years can be obtained by computer simulation in a short time. (Advantages and disadvantages of simulation, moderate)

{AACSB: Use of IT}

67.Explain the difference between random numbers and random number intervals.

Random numbers are a series of digits that have been selected by a totally random process. Random number intervals are numbers used to represent each possible value or outcome in a computer simulation. During simulation, a particular random number is matched against the random number intervals to determine the value for the element being modeled that particular time. (Monte Carlo simulation, moderate)

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