OPERATIONS MANAGEMENT IN THE SUPPLY CHAIN: DECISIONS & CASES (Mcgraw-hill Series Operations and Decision Sciences)
7th Edition
ISBN: 9780077835439
Author: Roger G Schroeder, M. Johnny Rungtusanatham, Susan Meyer Goldstein
Publisher: McGraw-Hill Education
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Question
Chapter 9, Problem 7P
a)
Summary Introduction
To determine: The upper and LCLs for X bar and R control charts.
b)
Summary Introduction
To determine: The action that should be taken.
c)
Summary Introduction
To discuss: The pros and cons of using a variable control chart instead of an attribute control chart.
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Students have asked these similar questions
A woodworker is concerned about the quality of the finished appearance of her work. She has finished a total of 50 unit split-willow hand-woven baskets. However, she has found the following number of finish defects in ten units sampled: 4,0,3,1,2,0,1,2,0,2.
Calculate the average number of defects per basket.
If 3-sigma control limits are used, calculate the lower control limit and upper control limit.
A Quality Analyst wants to construct a control chart for determining whether three machines, all producing the same product, are under control with regard to a particular quality variable. Accordingly, he sampled four units of output from each machine, with the following results:
For upper and lower control limits of 23.29 and 16.71, which machine(s), if any, appear(s) to have an out-of-control process mean?
Your supervisor, Lisa Lehmann, has asked that you report on the output of a machine on the factory floor. This machine is supposed to be producing optical lenses with a meanweight of 50 grams and a range of 3.5 grams. The following table contains the data for a sample size of n = 6 taken during the past 3 hours: a) What are the :X-chart control limits when the machine is working properly?b) What are the R-charL control limits when the machine is working properly?c) What seems to be happening? (Hint: Graph the data points. Run charts may be helpful.)
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OPERATIONS MANAGEMENT IN THE SUPPLY CHAIN: DECISIONS & CASES (Mcgraw-hill Series Operations and Decision Sciences)
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- Resistors for electronic circuits are manufactured on a high-speed automated machine. The machine is set up to produce a large run of resistors of 1,000 ohms each. Use Exhibit 13.7. To set up the machine and to create a control chart to be used throughout the run, 15 samples were taken with four resistors in each sample. The complete list of samples and their measured values are as follows: Use three-sigma control limits. c. Determine the UCL and LCL for a X−X− chart. (Round your answers to 3 decimal places.) d. Determine the UCL and LCL for R-chart. (Leave no cells blank - be certain to enter "0" wherever required. Round your answers to 3 decimal places.)arrow_forwardA shirt manufacturer buys clothes by the 100-yard roll from a supplier. For setting a control chart to manage the irregularities (e.g., loose threads and tears), the following data were collected from a sample provided by the supplier. Sample 1 2 3 4 5 6 7 8 9 10 Irregularities 3 5 2 6 5 4 6 3 4 5 Which type of control chart should be used? Construct a control chart with two-sigma control limits. Suppose the next five rolls from the supplier had three, two, five, three, and seven irregularities. Is the supplier process under control? Explain and show workarrow_forwardAspen Plastics produces plastic bottles to customer order. The quality inspector randomly selects four bottles from the bottle machine and measures the outside diameterof the bottle neck, a critical quality dimension that deter- mines whether the bottle cap will fit properly. The dimensions (in.) from the last six samples are Questions : Assume that only these six samples are sufficient, and use the data to determine control limits for an R- and an x-chart. Suppose that the specification for the bottle neck di- ameter is 0.600 { 0.050 and the population standard deviation is 0.013 in. What is the Process Capability Index? The Process Capability Ratio? If the firm is seeking four-sigma performance, is the process capable of producing the bottle?arrow_forward
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- A Quality Analyst wants to construct a control chart for determining whether three machines, all producing the same product, are under control with regard to a particular quality variable. Accordingly, he sampled four units of output from each machine, with the following results : Machine #1 measurements [14, 13, 24, 22]; Machine #2 measurements [ 14, 19, 23, 14]; Machine #3 measurements [ 14, 16, 13, 16]. Using the factors for three sigma control limits, what are x-bar chart upper and lower control limits? a. 24.65and 9.013 b. 22.43and 11.24 c. 18.9and 14.76 d. 39.83and -6.167arrow_forward50 motor generators are inspected per day from a stable process. The best estimate of the fraction of nonconforming is 0.076. Determine the centeral line and control limits. On a particular day, 5 nonconforming generators were discovered. Is this process in or out of control? For the information given in the problem, construct a np-chartarrow_forwardAt Quick Car Wash, the wash process is advertised to take less than 7 minutes. Consequently, management has set a target average of 390 seconds for the wash process. Suppose the average range for a sample of 9 cars is 8 seconds. Use the accompanying table to establish control limits for sample means and ranges for the car wash process. LOADING... Click the icon to view the table of factors for calculating three-sigma limits for the x overbarx-chart and R-chart. Factors for calculating three-sigma limits for the x overbarx-chart and R-chart Size of Sample (n) Factor for UCL and LCL for x overbarx-chart (Upper A 2A2) Factor for LCL for R-Chart (Upper D 3D3) Factor for UCL for R-Chart (Upper D 4D4) 2 1.8801.880 00 3.2673.267 3 1.0231.023 00 2.5752.575 4 0.7290.729 00 2.2822.282 5 0.5770.577 00 2.1152.115 6 0.4830.483 00 2.0042.004 7 0.4190.419 0.0760.076 1.9241.924 8 0.3730.373…arrow_forward
- At Quick Car Wash, the wash process is advertised to take less than 7 minutes. Consequently, management has set a target average of 390 seconds for the wash process. Suppose the average range for a sample of 9 cars is 8 seconds. Use the accompanying table to establish control limits for sample means and ranges for the car wash process. LOADING... Click the icon to view the table of factors for calculating three-sigma limits for the x overbarx-chart and R-chart. Factors for calculating three-sigma limits for the x overbarx-chart and R-chart Size of Sample (n) Factor for UCL and LCL for x overbarx-chart (Upper A 2A2) Factor for LCL for R-Chart (Upper D 3D3) Factor for UCL for R-Chart (Upper D 4D4) 2 1.8801.880 00 3.2673.267 3 1.0231.023 00 2.5752.575 4 0.7290.729 00 2.2822.282 5 0.5770.577 00 2.1152.115 6 0.4830.483 00 2.0042.004 7 0.4190.419 0.0760.076 1.9241.924 8 0.3730.373…arrow_forwardA quality inspector took five samples in five hours, each with four observations, of the length time for glue to dry. The analyst compute the mean of each sample and the computed the grand mean. All values are in minutes. Use this information to obtain three-sigma control limits for means. It is known from previous experience that the standard deviation of the process is 0.02 minutes. Draw a control chart Please provide a step-by-step solutionarrow_forwardA metal fabricator produces connecting rods with an outer diameter that has a 1 ± .01–inch specification. A machine operator takes several sample measurements over time and determines the sample mean outer diameter to be 1.002 inches with a standard deviation of .003 inch.a. Calculate the process capability index for this example.b. What does this figure tell you about the process?arrow_forward
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