SCM 352 Exam 2 Study Guide PDF

SCM 352 Exam 2 Study Guide Material: Homeworks 4, 5, 6, and 7 Managing Quality Discussion Questions: 1. Define quality (use American Society for Quality definition). - “The totality of features and characteristics of a product or service that bears on i...

SCM 352 Exam 2 Study Guide Material: Homeworks 4, 5, 6, and 7 Managing Quality Discussion Questions: 1. Define quality (use American Society for Quality definition). - “The totality of features and characteristics of a product or service that bears on its ability to satisfy stated or implied needs.” 2. Explain how improving quality can lead to reduced costs. - Improving quality leads to reduced costs because there could be less defects or replacements needed, and efficiency can be increased 3. Name and briefly explain nine dimensions of quality. - Performance, Features, Serviceability, Aesthetics – sensory attributes, Reliability, Perceived Quality, Conformance, Durability, Safety 4. What is included in the cost of quality? Name four components and briefly describe each. - Cost of Conformance: Prevention costs – reducing the potential for defects. Appraisal costs – evaluating products, parts, and services. Cost of Non-conformance: Internal failure – producing defective parts or service before delivery. External costs – costs discovered after delivery. 5. List the seven concepts that are necessary for an effective TQM program. - Continuous improvement: Involves all operations and work centers including suppliers and customers. End goal is perfection, never achieved, Kaizen - Six Sigma: Two meanings – one statistical, other – A program designed to reduce defects, lower costs, and improve customer satisfaction. - Employee Empowerment: Getting employees involved in product and process improvements - Benchmarking: Selecting best practices to use as a standard for performance - Just in Time (JIT) – designed to produce/deliver goods as required - Taguchi methods – statistical methods to improve quality of manufactured goods. 3 concepts: Quality robustness, Target oriented quality, Quality loss function - TQM Tools: Tools designed for generating ideas, organzing data, and identifying problems. 6. What is the meaning of Six Sigma? - Highly structured approach to process improvement, statistically is a process that is 99.9997% capable, 3.4 defects per million opportunities (DPMO) 7. What are seven tools of TQM? Name and briefly describe. - Check sheet, Scatter diagram, cause and effect diagram (fish bone), Pareto chart, Flow chart, Histogram, Statistical process control chart. Capacity and Constraint Management 1 Discussion Questions: 1. Distinguish between design capacity and effective capacity. - Desigin capacity – max theoretical output of a system in a given period under ideal conditions. Effective capacity – capacity a firm expects to achieve given current operating constraints. Often lower than design capacity. 2. What is utilization? - Percent of design capacity achieved: Actual output/design output 3. What is efficiency? - Percent of effective capacity achieved: Actual output/effective capacity 4. What is the theory of constraints? - A body of knowledge that deals with anything that limits or constrains organizations ability to achieve its goals. 5. Distinguish between bottleneck time and throughput time. - Bottleneck time: operation that is the limiting factor or constraint, time of the longest or slowest process. Throughput time: time it takes for a product to go through the production process with no waiting. 6. What are the 5 steps for managing constraints? - 1. Identify the constraints - 2. Develop a plan for overcoming the constraints - 3. Focus resources on accomplishing previous step - 4. Reduce the effects of constraints by offloading work or expanding capability - 5. Once overcome, find new constraints. Problems: 1. A plant has an effective capacity of 900 units per day and produces 800 units per day. What is its efficiency? 2. A university’s business program has the facilities and faculty to handle an enrollment of 2,000 new students per year. However, conflicting schedules allowed only 1,450 students to take business courses. What is the utilization of this system? 3. T. Smunt Manufacturing Corp has the process displayed below. The drilling operation occurs simultaneously with the sanding operations. The product needs to go only one of the three assembly operations. a. Which operation is the bottleneck? b. What is the bottleneck time? c. What is the throughput time? 2  Sawing Assembly Sanding 15 min/unit 28 min/unit 15 min/unit Welding Assembly Drilling 25 min/unit 28 min/unit 27 min/unit Assembly 28 min/unit Linear Programming Discussion Questions: 1. What is LP? - A mathematical technique to help plan and make decisions relative to the trade offs necessary to allocate resources. Will find the minimum or maximum of the objective function. Guarantees the optimal solution to the model is formulated. 2. What are the four requirements for applying a LP technique? - 1. Objective: LP Problems seek to maximize or minimize some quantity (usually profit or cost) expressed as an objective function. - 2. Constraints: The presence of restrictions or constraints which limit the degree to which we can pursue our objective - 3. Alternatives: There must be alternative courses of action to choose from - 4. Linearity: The objective and constraints in linear programming problems must be expressed in terms of linear equations or inequalities. 3. Describe steps in solving a LP problem using a graphical solution. 4. Describe the steps for using the corner-point method. 1. Construct a table 2. Write the objective functionand the constraints as linear equation 3. Plot the constraints 4. Identify the area of physical solutions (shaded area) 5. Identify coordinate points around that area 6. Plug the coordinates of each corner point into the objective function 7. Choose optimal solution 5. What is a feasible solution of a graphical LP problem? - A feasible solution is anything within the area or on the area created with the linear programming graphs 3  6. What is shadow price and how can it be interpreted? - Is the change in the value of the objective function resulting from a one unit change in the right hand side value of the constraint. Used to answer the question of how much would you pay for one additional unit of a resource? Problems: 1. Johnson’s, a Los Angeles, CA, clothing manufacturer that produces men’s shirts and pajamas, has two primary resources available: sewing machine time and cutting machine time. Over the next month, owner Andrew Johnson can schedule up to 280 hours of work on sewing machines and up to 450 of work on cutting machines. Each shirt produced required 1.00 hours of sewing time and 1.50 hours of cutting time. Producing each pair of pajamas required 0.75 hours of sewing time and 2 hours of cutting time. Each shirt produced will yield a $4 contribution to profit, and each pair of pajamas will yield a $3 contribution to profit. Solve the problem using the graphical and corner-point method. 2. Holiday Meal Turkey Ranch is considering buying two different types of turkey feed. Each feed contains, in varying proportions, some or all of the three nutritional ingredients essential for fattening turkeys. Brand Y feed costs the ranch $0.02 per pound. Brand Z costs $0.03 per pound. The rancher would like to determine the lowest-cost diet that meets the minimum monthly intake requirements for each nutritional ingredient. The following table contains relevant information about the composition of brand Y and brand Z feeds, as well as the minimum monthly requirement for each nutritional ingredient per turkey. Ingredient Brand Y Feed Brand Z Feed Min Monthly Requirement A 5 oz 10 oz 90 oz B 4 oz 3 oz 48 oz C 0.5 oz 0 1.5 oz Cost/lb $0.02 $0.03 Waiting-Line Models Discussion Questions: 1. Name the three parts of a typical queuing system. - Arrival, Waiting line, and Service 2. Describe and discuss arrival characteristics - Size of the arrival population, Pattern of arrivals, behavior of arrivals 3. Which probability distribution usually describes the number of arrivals per unit of time? - a/b/c: a = probability distribution of customers arrival b = probability distribution of service time, c= number of servers 4. Which probability distribution usually describes the service time? - Refer to above question 4  5. What is ‘balking’? - Balking describes a situation where a customer decides not to enter a queue because it is too long or they anticipate waiting too long 6. What is ‘reneging’? - Concept where a customer joins a queue but then decides to leave the queue due to long waiting lines 7. Describe and discuss characteristics of the waiting line 8. Queue length: limited or unlimited, Queue discipline: FIFO is most common, other prioriy rules may be used in special circumstances. 9. Describe and discuss characteristics of the service facility - Service time distribution: can be either constant or random, random services tend to follow negative exponential probability distribution (which means that the probability of a very long service time is very low). Queuing system designs: Number of servers: single server vs multiple server, number of phases single or multiphase 10. Describe service facility designs - Refer to graphs for study material 11. State the assumptions of model M/M/1 - Single channel system, service time pattern is negative exponential 12. State the assumptions of model M/D/1 - Constant service, same everything else as MM1 which is single servers and phases, Poissan arrival rate pattern, population size is unlimited, and queue discipline is FIFO. Problems: 1. Customers arrive at Rich Dunn’s Styling Shop at a rate of 3 per hour, distributed in a Poisson fashion. Rich’s service times follow a negative exponential distribution, and Rich can complete an average haircut takes 12 minutes. a. Find the average number of customers waiting for haircuts. b. Find the average number of customers in the shop. c. Find the average time a customer waits until it is his/her turn. d. Find the average time a customer spends in the shop. e. Find the percentage of time that Rich is busy. 2. There is only one copying machine in the student lounge of the business school. Students arrive at the rate of 40 per hour (according to a Poisson distribution). Copying take an average of 40 seconds (according to a negative exponential distribution). Compute the following: a. The percentage of time that the machine is used. b. The average length of the queue. c. The average number of students in the system. d. The average time spent waiting in the queue. e. The average time in the system. 3. Altug’s Coffee Shop decides to install an automatic coffee vending machine outside one of its stores to reduce the number of people standing in line inside. Mehme Altug charged 5  $3.50 per cup. However, it takes too long for people to make change. The service time is a constant 3 minutes, and the arrival rate is 15 per hour (Poisson distributed). a. What is the average wait in line? b. What is the average number of people in line? c. Mehmet raises the price to $5 per cup and takes 60 seconds off the service time. However, because the coffee is now so expensive, the arrival rate drops to 10 per hour. Now what are the average wait time and the average number of people in the queue waiting? 4. Renuka Jain’s Car Wash takes a constant time of 4.5 minutes in its automated car wash cycle. Autos arrive following a Poisson distribution at the rate of 10 per hour. Renuka wants to know: a. The average waiting time in line. b. The average length of the line. 6