Q&A Hero

Q: Consider these data regarding the multiple-server, priority service queuing model: Service Rate: 2 per hour (Poisson) Number of Servers: 5 What is the average number of all items waiting in line for service?

Q: Customers arrive at a video rental desk at the rate of one per minute (Poisson). Each server can handle .40 customers per minute (Poisson). (A) If there are four servers, determine: (1) The average time it takes to rent a video (2) The probability of three or fewer customers in the system (B) What is the minimum number of servers needed to achieve an average time in the system of less than three minutes?

Q: A department has five machines that each run for an average of 8.4 hours (exponential) before service is required. Service time average is 1.6 hours (exponential). (A) While running, each machine can produce 120 pieces per hour. With one server, what is the average hourly output actually achieved? (B) With two servers, what is the probability that a machine would be served immediately when it requires service? (C) If machine downtime cost is $100 per hour per machine, and server time costs $30 per hour, how many servers would be optimal?

Q: Two troubleshooters handle service calls for 10 machines. The average time between service requirements is 18 days, and service time averages two days. Assume exponential distributions. While running, each machine can produce 1,500 pieces per day. Determine: (A) the percentage of time troubleshooters are idle. (B) each machine's net productivity. (C) If troubleshooters represent a cost of $150 per day, and machine downtime cost is $600 per day, would another troubleshooter be justified? Explain.

Q: A department has five semiautomatic pieces of equipment which operate for an average of 79 minutes before they must be reloaded. The reloading operation takes an average of 21 minutes per machine. Assume exponential distributions. What is the minimum number of servers needed to keep the average downtime per cycle to less than 25 minutes?

Q: Customers filter into a record shop at an average of one per minute (Poisson) where the service rate is 15 per hour (Poisson). Determine the following: (A) the average number of customers in the system with eight servers (B) the minimum number of servers needed to keep the average time in the system to under six minutes

Q: During the early morning hours, customers arrive at a branch post office at an average rate of 45 per hour (Poisson), while clerks can handle transactions in an average time (exponential) of four minutes each. Find: (A) the average number of customers waiting for service if six clerks are used. (B) the minimum number of clerks needed to keep the average time in the system to under five minutes. (C) If clerk cost is $30 per hour and customer waiting time represents a "cost" of $20 per hour, how many clerks can be justified on a cost basis?

Q: Customers arrive at a suburban ticket outlet at the rate of 14 per hour on Monday mornings. This can be described by a Poisson distribution. Selling the tickets and providing general information takes an average of three minutes per customer, and varies exponentially. There is one ticket agent on duty on Mondays. Determine each of the following: (A) system utilization (B) average number in line (C) average time in line (D) average time in the system

Q: In a multichannel system with multiple waiting lines, customers shifting among the waiting lines is an example of: A. departing. B. utilizing. C. abandoning. D. balking. E. jockeying.

Q: Which of the following would reduce perceived waiting times most dramatically in a doctor's office? A. putting all clocks out of sight B. removing couches C. having the patient fill out forms D. implementing a "no-cell-phone" policy E. keeping expected waiting times from the patients

Q: A restaurant that implements a limited menu and a "no substitutions" policy during peak dining hours is practicing _____________ with respect to waiting-line management. A. demand shifting B. queuing psychology C. service standardization D. service phasing E. outsourcing

Q: Offering an "early bird" special at a restaurant to reduce waiting times during peak hours is an example of: A. demand shifting. B. queuing psychology. C. service phasing. D. service standardization. E. outsourcing.

Q: A restaurant at a popular Colorado casino provides priority service to player's card holders. The restaurant has 10 tables or booths where customers may be seated. The service time (time a booth or table is occupied) averages 40 minutes once a party is seated. The customer arrival rate is 12 parties per hour, with the parties being equally divided between card holders and people without player's cards. On average, how much longer do parties without player's cards spend in the system, compared to parties with the player's cards? A. 2 minutes B. 4 minutes C. 8 minutes D. 10 minutes E. It is impossible to say without more information.

Q: A restaurant at a popular Colorado casino provides priority service to player's card holders. The restaurant has 10 tables or booths where customers may be seated. The service time (time a booth or table is occupied) averages 40 minutes once a party is seated. The customer arrival rate is 12 parties per hour, with the parties being equally divided between card holders and people without player's cards. On average, how many parties without player's cards are waiting to be seated? A. 0.52 B. 0.41 C. 0.88 D. 1.23 E. 1.75

Q: A restaurant at a popular Colorado casino provides priority service to player's card holders. The restaurant has 10 tables or booths where customers may be seated. The service time (time a booth or table is occupied) averages 40 minutes once a party is seated. The customer arrival rate is 12 parties per hour, with the parties being equally divided between card holders and people without player's cards. On average, how many parties with player's cards are waiting to be seated? A. 0.52 B. 0.41 C. 0.88 D. 1.23 E. 1.75

Q: A restaurant at a popular Colorado casino provides priority service to player's card holders. The restaurant has 10 tables or booths where customers may be seated. The service time (time a booth or table is occupied) averages 40 minutes once a party is seated. The customer arrival rate is 12 parties per hour, with the parties being equally divided between card holders and people without player's cards. What is the average time that parties without player's cards wait to be seated? A. approx. 4 minutes B. approx. 8 minutes C. approx. 12 minutes D. approx. 15 minutes E. approx. 2 minutes

Q: A restaurant at a popular Colorado casino provides priority service to player's card holders. The restaurant has 10 tables or booths where customers may be seated. The service time (time a booth or table is occupied) averages 40 minutes once a party is seated. The customer arrival rate is 12 parties per hour, with the parties being equally divided between card holders and people without player's cards. What is the average time that player's card holders wait to be seated? A. approx. 4 minutes B. approx. 8 minutes C. approx. 12 minutes D. approx. 15 minutes E. approx. 2 minutes

Q: A bank is designing a new branch office and needs to determine how much driveway space to allow for cars waiting for drive-up teller service. The drive-up service will have three tellers and a single waiting line. At another branch of the bank in a similar setting, the average service time for drive-up tellers is four minutes per customer, and average arrival rate is 36 customers per hour. It is expected that the new bank will have similar characteristics. How many spaces should be provided to have a 96 percent probability of accommodating all of the waiting cars? A. 10 B. 11 C. 12 D. 13 E. 14

Q: A bank of 10 machines requires regular periodic service. Machine running time and service time are both exponential. Machines run for an average of 44 minutes between service requirements, and service time averages six minutes per machine. If operators cost $15 per hour in wages and fringe benefits and machine downtime costs $75 per hour in lost production, what is the optimal number of operators for this bank of machines? A. 1 B. 2 C. 3 D. 4 E. 5

Q: A bank of 10 machines requires regular periodic service. Machine running time and service time are both exponential. Machines run for an average of 44 minutes between service requirements, and service time averages six minutes per machine. What is the average number of machines down when there is one operator? A. 1.49 B. 3.35 C. 4.40 D. 6.65 E. 8.51

Q: A bank of 10 machines requires regular periodic service. Machine running time and service time are both exponential. Machines run for an average of 44 minutes between service requirements, and service time averages six minutes per machine. What is the average machine downtime with two operators? A. 1.71 minutes B. 3.46 minutes C. 6.25 minutes D. 7.71 minutes E. 9.46 minutes

Q: Consider the following work breakdown structure: What is the total cost of reducing the project to 18 weeks?

Q: Consider the following work breakdown structure: In crashing this project to 18 weeks, which activities (in order of selection) will be reduced?

Q: Consider the following work breakdown structure: In crashing this project, which activity should be the first to be reduced?

Q: Consider the following work breakdown structure: What activities make up the critical path?

Q: Consider the following work breakdown structure: Within what amount of time (in weeks) is there a 90 percent probability that the critical path for this project will be completed? 95 percent? 99 percent?

Q: Consider the following work breakdown structure: What is the probability that the critical path for this project will be completed within 75 weeks? 80 weeks? 85 weeks? 90 weeks?

Q: Consider the following work breakdown structure: What is the estimated standard deviation (in weeks) for the critical path completion time?

Q: Consider the following work breakdown structure: What is the critical path for this project network?

Q: Consider the following work breakdown structure: What are the estimated slack times (in weeks) for activities A-H?

Q: Consider the following work breakdown structure: What is the estimated expected (mean) time (in weeks) for project completion?

Q: Consider the following work breakdown structure: What are the estimated standard deviations (in weeks) in the times for activities A-H?

Q: Consider the following work breakdown structure: What are the estimated expected (mean) times (in weeks) for activities A-H?

Q: What is the probability that this project will take more than 10 weeks to complete if the activity means and standard deviations are as shown below?

Q: Activity D has an optimistic time of three days, a pessimistic time of nine days, and a most likely time of four days. Determine its expected time and variance.

Q: A project has the activities and activity times (days) listed below. Determine the probability that the project will require more than 15 days from start to finish.

Q: Prepare a crashing plan for the following project that will reduce the project duration by three weeks.

Q: Activity E has an optimistic time of 9 days, a most likely time of 12 days, and a pessimistic time of 15 days. Estimate its expected time and standard deviation.

Q: A project consists of nine major activities, as shown below. There are three separate paths in the network: a-c-f, b-d-g, and e-h-i. (A) What is expected project duration time? (B) Determine the probability that the project will take more than 35 weeks to complete. (All times are in weeks.)

Q: Given the network diagram below, determine the probability that the project will finish within 26 weeks of its start. Times on the diagram are in weeks.

Q: Determine the amount of slack in each of a project's activities (presented below), and identify those that are on the critical path.

Q: In the project network presented below, numbers on each arrow refer to the expected time and standard deviation in weeks for that particular activity. For example, "8,2" indicates an activity with an expected time of 8 and a standard deviation of two weeks. For this project, determine each of the following: (A) the activities which are on the critical path (B) the expected project duration (C) the probability that the project will be completed in 29 weeks or less

Q: Using the information given in the following table: (A) Identify the critical path. (B) Determine expected project duration.

Q: Consider the project depicted by the following A-O-A diagram: What is the probability that this project's duration will exceed 8.5 weeks?

Q: Activity J has a duration of 7 and an earliest finish time of 21. If J's latest start time is 16, this must mean that J's slack is: A. 7. B. 4. C. 3. D. 2. E. 1.

Q: If an activity is determined to be on the critical path, that means that it, and perhaps others, will affect project: A. direct costs. B. performance. C. quality. D. conflict. E. duration.

Q: Which of the following is not an element of the project management triangle? A. cost B. schedule C. resources D. quality E. performance objectives

Q: Which of the following leads to simulation being a useful tool with uncertain activity times? A. paths that are not independent B. activity times that are not deterministic C. activity times that cannot be crashed D. noncritical paths that have no variability E. critical paths with activities with deterministic time estimates

Q: Which of the following is not characteristic of good risk management? A. estimating the likelihood of chance events occurring B. planning to eliminate chance events C. identifying potential chance events D. formulating contingency plans for chance events E. analyzing the consequences of chance events

Q: Consider the following work breakdown structure: What is the estimated slack time for activity W? A. 0 days B. 25 days C. 35 days D. 45 days E. 85 days

Q: Consider the following work breakdown structure: What is the probability that this project will be completed within 130 days? A. .8413 B. .90 C. .9544 D. .9772 E. .9987

Q: A project is represented by the following diagram: The critical path for the network shown is: A. 1-3-6-7. B. 1-2-4-7. C. 1-4-7. D. 1-3-4-7. E. 1-2-5-7.

Q: A project is represented by the following diagram: The expected duration of this project is: A. 13. B. 15. C. 20. D. 52. E. 81.

Q: Gantt charts are most closely associated with A. JIT. B. PERT. C. MRP. D. MRPII. E. Six Sigma.

Q: Which of the following is not a limitation of PERT and similar project-scheduling techniques? A. They force the manager to organize and quantify information. B. One or more important activities may be omitted from the network. C. Precedence relationships may not all be correct as shown. D. Time estimates may contain a "fudge factor." E. The use of a computer is essential for large projects.

Q: Which of the following are limitations of PERT? (I) Time estimates may include a fudge factor. (II) Important activities may be overlooked. (III) It is an after-the-fact analysis. A. I and II B. I, II, and III C. I and III D. II and III E. I only

Q: Which of the following are advantages of PERT? (I) It is visual. (II) It is automatically updated. (III) Activities that need to be watched closely can be identified. A. I and II B. II and III C. III only D. I and III E. I, II, and III

Q: At which point does crashing of a project cease? A. when the project is completed B. when no additional crashing is possible C. when the cost to crash equals or exceeds the benefit of crashing D. when the project is one-half completed E. when the team has been disbanded

Q: In "crashing" a project, a manager will generally focus on activities which: A. are not on the critical path. B. are the least costly to crash. C. are costly to crash and are on the critical path. D. are on the critical path and are the least costly to crash. E. are the easiest to crash.

Q: The project management strategy of injecting additional resources in order to reduce the length of the project is called: A. expediting. B. rushing. C. panicking. D. crashing. E. loading.

Q: There are four activities on the critical path. Coincidentally, their standard deviations are all equal to 4. The standard deviation of the critical path is therefore equal to: A. 2. B. 4. C. 8. D. 16. E. 64.

Q: There are four activities on the critical path, and they have standard deviations of 1, 2, 4, and 2 days. The standard deviation of the critical path is: A. 3. B. 5. C. 9. D. 16. E. 25.

Q: Activity 4-5 in a network diagram has an optimistic time estimate of five days, a most likely time estimate of seven days, and a pessimistic time estimate of 10 days. Its expected time (in days) is approximately: A. 5. B. 6. C. 7. D. 8. E. 9.

Q: A PERT/CPM activity has an optimistic time estimate of three days, a most likely time estimate of eight days, and a pessimistic time estimate of 10 days. The expected time (in days) of this activity is: A. 7.0. B. 7.5. C. 8.0. D. 8.5. E. 10.0.

Q: When developing probabilistic estimates of project duration, it is necessary to know which of the following? A. the mean and variance of every activity B. the mean and variance of activities on the critical path C. the standard deviation of activities on the critical path D. each activity's probability of completion E. the distribution of activity times

Q: The basis for use of the beta distribution in PERT is: A. essentially theoretical. B. its adaptability. C. its symmetry. D. It is bimodal. E. It can easily be converted to a normal distribution.

Q: In the probabilistic approach to project network analysis, the time estimate annotated tm for any activity is the: A. mean time. B. median time. C. most likely time. D. mode time. E. marginal time.

Q: Given this information about activity 3-4: ES = 10, EF = 15, LS = 16, and LF = 21, we can determine that the amount of slack associated with the activity is: A. 0. B. 1. C. 5. D. 6. E. 11.

Q: Activity C has an early start time of 8, an early finish time of 12, a latest start time of 13, and a latest finish time of 17. Its slack is: A. 0. B. 1. C. 4. D. 5. E. 9.

Q: In project network analysis, "slack" refers to the difference between: A. observed and predicted times. B. optimistic and pessimistic times. C. mean and modal times. D. finish and start times. E. latest and earliest times.

Q: A node has one entering activity, a, and two leaving activities, b and c. Given the following information, determine the latest starting time for activity a: EFb = 15, EFc = 17, LFb = 24, LFc = 27; activity times are a = 4, b = 6, c = 8. A. 14 B. 15 C. 16 D. 17 E. 18

Q: Consider the portion of a project depicted by this graph: What is the latest start time of activity 6-7 if the latest finish of activity 7-8 is 26, and the latest finish of activity 7-9 is 23? A. 18 B. 17 C. 13 D. 12 E. 10

Q: Which of the following is determined as a direct result of computing the earliest starting and finishing times for the activities of a project network? A. expected project duration B. activity slack time C. which activities are on the critical path D. variance in project duration E. maximum project duration

Q: Activity 7-8 is directly preceded by two activitiesactivity 5-7 and activity 6-7. Activity 5-7 has an expected time of five and an ES time of six. Activity 6-7 has an expected time of seven and an ES time of seven. Activity 7-8 has an expected time of 10. The ES for activity 7-8 is: A. 11. B. 14. C. 21. D. 24. E. 25.

Q: Shortening activity durations is called: A. expediting. B. crashing. C. vendor management. D. null nodes. E. trade-off analysis.

Q: Which of the following is not true about the use of dummy activities in project networking? A. They preserve the separate identities of activities. B. They clarify precedence relationships among activities. C. They have an activity time equal to zero. D. They have an activity time variance equal to zero. E. They are used in activities-on-nodes (AON) network diagrams.

Q: In a project network, the critical path is the sequence of activities which has the: A. most activities. B. most nodes. C. most events. D. longest duration. E. greatest variance.

Q: The advantage a precedence diagram has over a Gantt chart is: A. its ability to reveal relationships among activities. B. its difficulty in depicting networks. C. its complexity. D. its simplicity. E. its lack of riskiness.

Q: Concerning PERT and CPM: A. These are two different names for essentially the same technique. B. CPM tends to focus more on the critical path; PERT focuses on the parallel paths. C. PERT gives a clearer indication of activity slack, while CPM gives a better picture of path slack. D. Because of its recent discovery, much less is known about CPM than PERT. E. CPM is useful for project manager selection; PERT is useful for project team selection.

Q: To _____ an activity means to shorten the time it will take. A. speed B. fund C. crash D. aggregate E. matrix