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6.12 Mary Beth Marrs, the manager of an apartmentcomplex, feels overwhelmed by the number of complaints sheis receiving. Below is the check sheet she has kept for the past12 weeks. Develop a Pareto chart using this information. Whatrecommendations would you make?WEEK GROUNDSPARKING/DRIVES POOLTENANTISSUESELECTRICAL/PLUMBING1 333 33 3 3332 3 333 33 33 33 333 333 33 34 3 3333 3 3 335 33 333 3333 336 3 3333 337 333 33 338 3 3333 33 333 39 3 33 310 3 3333 33 3311 333 33 312 33 333 333 3(the "3's" represent check marks FYI) (I will upload the chapter so maybe you can view it if this is still too confusing)S6.11 Twelve samples, each containing five parts, were takenfrom a process that produces steel rods. The length of each rod inthe samples was determined. The results were tabulated and samplemeans and ranges were computed. The results were:SAMPLE SAMPLE MEAN (in.) RANGE (in.)1 10.002 0.0112 10.002 0.0143 9.991 0.0074 10.006 0.0225 9.997 0.0136 9.999 0.0127 10.001 0.0088 10.005 0.0139 9.995 0.00410 10.001 0.01111 10.001 0.01412 10.006 0.009a) Determine the upper and lower control limits and the overallmeans for x-charts and R-charts.b) Draw the charts and plot the values of the sample means andranges.c) Do the data indicate a process that is in control?d) Why or why not?S6.20 Jamison Kovach Supply Company manufactures paperclips and other office products. Although inexpensive, paper clipshave provided the firm with a high margin of profitability. Samplesize is 200. Results are given for the last 10 samples:SAMPLE 1 2 3 4 5 6 7 8 9 10DEFECTIVES 5 7 4 4 6 3 5 6 2 8a) Establish upper and lower control limits for the control chart andgraph the data.b) Is the process in control?c) If the sample size were 100 instead, how would your limits andconclusions change?S6.23 The school board is trying to evaluate a new mathprogram introduced to second-graders in five elementary schoolsacross the county this year. A sample of the student scores onstandardized math tests in each elementary school yielded the followingdata:SCHOOL NO. OF TEST ERRORSA 52B 27C 35D 44E 55Construct a c-chart for test errors, and set the control limitsto contain 99.73% of the random variation in test scores.What does the chart tell you? Has the new math program beeneffective?S6.27 Meena Chavan Corp.’s computer chip production processyields DRAM chips with an average life of 1,800 hours ands = 100 hours. The tolerance upper and lower specification limitsare 2,400 hours and 1,600 hours, respectively. Is this process capableof producing DRAM chips to specification?S6.35 One of New England Air’s top competitive prioritiesis on-time arrivals. Quality VP Clair Bond decided to personallymonitor New England Air’s performance. Each week for the past30 weeks, Bond checked a random sample of 100 flight arrivals foron-time performance. The table that follows contains the number offlights that did not meet New England Air’s definition of “on time”:SAMPLE(WEEK)LATEFLIGHTSSAMPLE(WEEK)LATEFLIGHTS1 2 16 22 4 17 33 10 18 74 4 19 35 1 20 26 1 21 37 13 22 78 9 23 49 11 24 310 0 25 211 3 26 212 4 27 013 2 28 114 2 29 315 8 30 4a) Using a 95% confidence level, plot the overall percentage of lateflights (p) and the upper and lower control limits on a controlchart.b) Assume that the airline industry’s upper and lower control limitsfor flights that are not on time are .1000 and .0400, respectively.Draw them on your control chart.c) Plot the percentage of late flights in each sample. Do all samplesfall within New England Air’s control limits? When one falls outsidethe control limits, what should be done?d) What can Clair Bond report about the quality of service?

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