Operations & Logistics Management ANSWER KEY 1st Examination MGMT E-5065

Examination Results Grade Section All Sections A B C D E F G

Multiple Choice 1. In the maturity stage of a product’s life cycle, a typical operations strategy would be: a. increasing capacity. b. short production runs. c. cost minimization. d. increases in process stability. 2. Which statement is true? a. the mission statement precedes analysis of external and internal factors. b. market segments are selected prior to development of the mission statement. c. functional strategy is formulated prior to corporate strategy. d. the marketing functional strategy dictates the pro- ducts and services that the firm will offer.

Multiple Choice Product innovation rates are a (an): a. a goal-based measure. b. a corporate goal. c. a productivity measure. d. an external factor. Supplier reliability is a(an): b. a functional strategy. c. an internal factor.

Multiple Choice 5. In the production of goods, as opposed to services: a. the customer may be directly involved. b. the facility should be near the customer. c. quality standards are precisely measured. d. production scheduling focuses on customer demand rate. Assume that we are using a waiting line model to analyze the number of service technicians needed to maintain machines in a factory. Our goal should be to: a. maximize productivity of the technicians. b. minimize the number of machines needing repair. c. minimize the downtime for individual machines. d. minimize the percent of idle time of the technicians. e. minimize the total cost ( maintenance plus downtime ).

Multiple Choice 7. Which of the following is NOT true about arrivals? a. random arrivals are independent of each other. b. random arrivals cannot be predicted exactly. c. the Poisson distribution is often used to represent the arrival pattern. d. service times often follow the negative exponential distribution. e. the exponential distribution is often used to repre- sent the arrival pattern. 8. The customer who arrives at a bank, sees a long line, and leaves to return another time is: a. balking. b. cropping. c. reneging. d. indeterminate. e. none of the above. Applied Management Science for Decision Making, 2e © 2014 Pearson Learning Solutions Philip A. Vaccaro , PhD

Multiple Choice Lines at banks where customers wait for a teller window are usually representative of a: a. single-channel, multiphase system. b. single-channel, single-phase system. c. multichannel, multiphase system. d. multichannel, single-phase system. e. none of the above. A specialty restaurant has developed a single drive-through window. Customers order, pay, and pick up their food at the same window. Arrivals follow a Poisson distribution, while service times follow an exponential distribution. If the average number of arrivals is six (6) per hour and the service rate is two (2) every fifteen (15) minutes, what is the average number of customers in the system? a. 0.50 b. 4.00 c. 2.25 d. 3.00 e. none of the above

Multiple Choice Given the problem statement in question 10, what is the average number of customers waiting in line be- hind the person being served? a. 0.50 b. 0.75 c. 2.25 d. 3.00 e. none of the above Given the problem statement in question 10, what proportion of the time is the server busy? a. 0.25 b. 0.50 c. 0.75 d. 2.25 e. 3.00

Multiple Choice Given the problem statement in question 10, how much time will elapse (in hours) from the time a customer enters the line until he/she leaves the restaurant? a. 0.50 b. 0.25 c. 0.75 d. 2.25 e. 3.00 At a local fast-food joint, cars arrive randomly at a rate of 12 every 30 minutes. It takes an average of 2 minutes to serve each arrival. The utilization factor for this system is: a. 0.467 b. 0.547 c. 0.800 d. 0.133 e. none of the above

Multiple Choice Given the problem statement in question 14, what is the average time in the queue for each arrival? a. 2 minutes b. 4 minutes c. 6 minutes d. 8 minutes e. 10 minutes 16. A business has three (3) fax machines. The toner in each machine needs to be changed after about five (5) hours of use. There is one (1) secretary who is responsible for the fax machine maintenance. It takes the secretary fifteen (15) minutes to replace the toner cartridge. What is the probability that two (2) fax machines need toner at the same time? (select closest value) a. .0130 b. .0909 c. .1286 d. .1415 e. .8576

Multiple Choice 17. A single automatic carwash with one bay and a cycle time of 2.5 minutes is what type of model? a. M/M/1 b. M/M/2 c. M/D/2 d. M/D/1 e. M/G/1 18. The utilization factor is defined as the: a. percent of time the system is idle. b. average percent of time the customers wait in line. c. average time the service system is open. d. average length of the service line. e. none of the above.

Multiple Choice In queuing analysis, total expected cost is the sum of expected ________plus expected________. a. service costs, arrival costs. b. facility costs, calling costs. c. calling costs, inventory costs. d. calling costs, waiting costs. e. service costs, waiting costs. Commonly obtained measures of a queuing system’s performance include: a. average time each customer spends in the system, and the probability that the service system will be idle. b. the average queue length, and the maximum time a customer may spend in the queue. c. maximum queue length, and the probability of a specific number of customers in the system. d. average queue length, and the probability that the waiting time will exceed a specified period.

Multiple Choice 21. A maintenance shop employing one mechanic and servicing 50 machines would be described as a: a. single-channel, priority system. b. multi-channel, infinite calling population system. c. single-channel, finite calling population system. d. multi-channel, finite calling population system. 22. The service faclity is a combination of: a. arrival rates and service rates. b. servers and customers. c. queue length and queue discipline. d. channels and phases.

True or False 23. In queuing theory, the theoretical frequency distribution of the system arrivals must be statistically identical to the observed frequency distribution of system arrivals. TRUE FALSE 24. The most common queuing models assume a service rate that is normally distributed. 25. In a restaurant, the average time spent in the system is the time between a customer’s arrival and departure.

True or False Given the value of ‘lambda’ ( λ ) , a theoretical frequency distribution for system arrivals can be identified. TRUE FALSE 27. All queuing systems exhibit first-in, first-out queue discipline.

True or False 28. It is impossible to develop a process that has zero variability. TRUE FALSE 29. Assignable variations in a process are also called natural variations. 30. An x-bar chart would be appropriate to monitor the number of defects in a production lot. 31. The central limit theorem provides the statistical foundation for control charts.

True or False If we are tracking quality of performance for a class of students, we should plot the pass/fail result on a p-chart. TRUE FALSE Sample sizes as small as five (5) can be used when building control charts. 34. If we are attempting to control the diameter of bowling balls, we will find a p-chart to be quite helpful. A c-chart would be appropriate to monitor the number of weld defects on the steel plates of a ship’s hull.

Multiple Choice Bags of pretzels are sampled to ensure proper weight. The overall average for the samples is nine (9) ounces. Each sample contains 25 bags. The standard deviation is estimated to be three (3) ounces. The upper control chart limit ( for 99.7% confidence ) for the average would be ____ ounces. a. 9.4 b. 18.0 c. 10.2 d. 7.2 e. 10.8 37. R-charts measure changes in: a. central tendency. b. degree of variation. c. number of defects per production lot. d. natural variations. e. none of the above.

Multiple Choice Bags of chocolate candy are sampled to ensure proper weight. The overall average for the samples is 36 ounces. Each sample contains twelve (12) bags. The average range is 1.3 ounces. The upper control chart limit for the average would be: a. 36.3458 b. 35.6542 c. 38.3101 d. 36.6279 e. 37.1258 Bags of tea are sampled to ensure proper weight. The overall average for the samples is eight (8) ounces. Each sample contains 10 bags. The average range is 0.1 ounces. What is the lower limit of the average chart? a. 7.9692 b. 8.0308 c. 7.9076 d. 8.0924 e. 8.1024

Multiple Choice The average range of a process for packaging cereal is 1.1 ounces. If the sample size is ten (10), find the upper control chart limit for the range chart. a. 0.245 b. 1.955 c. 1.777 d. 0.223 e. 0.143 Given the problem statement in question 40, find the lower control chart limit for the range chart.

Multiple Choice Defects in computer hard-drives will usually render the entire computer worthless. For a particular model, the percent defective in the past has been 1%. If a sample size of 400 is taken, what would the 95.5% lower control chart limit be? a. 0.00995 b. 0.00005 c. 0.00000 d. 0.01000 e. 0.09550 Defects in marble countertops usually require the whole top to be reconstructed. In one kitchen shop, the percent defective in the past has been one (1) percent. If a sample size of 30 is taken, what should be the 95.5% upper control limit? a. 0.030 b. 0.000 c. 0.046 d. 0.064 e. 0.074

Multiple Choice A firm has been receiving complaints about the attitude of some sales clerks. Over a 10-day period, the total number of complaints was 360. The firm wishes to develop a control chart for the number of complaints. What would the upper control limit on the number of complaints per day be for a 3 sigma ( 99.7% ) control chart? a. 18 b. 36 c. 42 d. 54 e. 62 Given the same problem statement above, the total number of complaints is now 250. What would the lower control limit on the number of complaints per day be for a 3 sigma ( 99.7% ) control chart? a. 20 b. 0 c. 15 d. 10 e. 202.6

Multiple Choice 46. Who introduced control charts in 1924? a. W. Edwards Deming b. Philip Crosby c. J.M. Juran d. William Shewhart e. Malcolm Baldrige To guarantee that cans of soda are properly filled, some cans are sampled and the amounts measured. The overall average for the samples is 12 ounces. Each sample contains 10 cans. The average range is 0.4 ounces. The lower control chart limit for the average would be: a. 12.1232 b. 11.8768 c. 13.2000 d. 12.3080 e. 11.5500

Multiple Choice 48. The control chart: a. focuses on the time dimension of a system. b. captures the natural variability in the system. c. can be used for categorical, discrete, or continuous variables. d. all of the above. Which of the following situations suggests a process that appears to be operating in a state of statistical control? a. a control chart with a series of consecutive points that are above the center line and a series of consecutive points that are below the center line. b. a control chart in which no points fall outside either the upper control limit or the lower control limit, and no patterns are present. c. a control chart in which several points fall outside the upper control limit.

Multiple Choice A political pollster randomly selects a sample of 100 voters each day for 8 successive days and asks how many will vote for the incumbent. The pollster wishes to construct a ‘p’ chart to see if the percentage favoring the incumbent candidate is too eratic. Sample (Day) Number Favoring Incumbent 1 57 2 57 3 53 4 51 5 55 6 60 7 56 8 59 What is the numerical value of the center line for the ‘p’ chart? a. .53 b. .56 c. .63 d. .66

Multiple Choice Given the problem statement above, what is the numerical value of the lower control limit for the ‘p’ chart? a. 0.37 b. 0.41 c. 0.50 d. 0.71 52. When using the shortest-route technique, the 1st step is to: a. connect the nearest node that minimizes the total distance to the origin. b. trace the path from the warehouse to the plant. c. determine he average distance traveled from source to end. d. find the nearest node to the origin and put a distance box by the node.

Multiple Choice 53. When using the shortest-route technique, the 2nd step is to: a. find the next-nearest node to the origin and put the distance in a box by the node. b. trace the path from the warehouse to the plant. c. determine the average distance traveled from source to end. d. find the furthest node from the origin and put a distance box by the node. e. none of the above. All the nodes must be connected in which of the following techniques? a. minimal-flow. b. maximal-spanning tree. c. shortest-route. d. maximal-flow. e. minimal-spanning tree.

Multiple Choice Given the following distances between destination nodes, what is the minimum distance that connects all the nodes? From To Distance 1 2 300 2 3 150 1 3 200 a. 450 b. 150 c. 350 d. 650 e. none of the above.

Multiple Choice Given the following distances between destination nodes, what is the minimum distance that connects all the nodes? From To Distance 1 2 100 1 3 200 2 3 100 2 4 150 2 5 200 3 4 150 3 5 300 4 5 250 4 6 200 5 6 100 a. 900 b. 650 c. 400 d. 1200 e. none of the above.

Multiple Choice Find the shortest route from Node 1 to Node 6: From Node To Node Distance 1 2 150 1 3 200 2 3 100 2 4 200 2 5 50 3 4 350 3 5 300 4 6 100 5 6 100 a. 300 b. 450 c. 550 d. 650 e. none of the above.

Multiple Choice 58. In network models, the lines connecting the nodes are called: a. bridges. b. arrows. c. spans. d. arcs. e. links. 59. The minimal-spanning technique ( minimal-spanning tree ) would best be used: a. to assign workers to jobs in the cheapest manner. b. to determine LAN network wiring within a building. c. to minimize traffic flow on a busy highway. d. by a trucking firm making frequent but repeatable drops. e. to determine the number of units to ship from each source to each destination.

Multiple Choice Find the shortest route from Node 1 to Node 4: From Node To Node Distance 1 2 250 1 3 400 1 4 600 2 3 50 2 4 300 3 4 200 a. 750 b. 500 c. 550 d. 600 e. 50

True or False 61. In the minimal-spanning tree technique, it is necessary to start at the last node in the network. TRUE FALSE 62. In the minimal-spanning tree technique, if there is a tie for the nearest node, that suggests that there may be more than one optimal solution. 63. In the minimal spanning-tree and shortest-route models, the points on the network are referred to as ‘nodes’.

True or False 64. The minimal-spanning tree technique and the shortest- route technique obtain the same optimal solution. TRUE FALSE The shortest-route technique finds the maximum flow of any quantity or substance through a network.

Operations & Logistics Management 1st Examination Operations & Logistics Management ANSWER KEY MGMT E-5065