# Operation and Supply Chain Management stuck

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### Question Description

Problem 10-3

 Checkout time at a supermarket is monitored using a mean and a range chart. Six samples of n = 20 observations have been obtained and the sample means and ranges computed:
 Sample Mean Range Sample Mean Range 1 3.06 .42 4 3.13 .46 2 3.15 .38 5 3.06 .46 3 3.11 .41 6 3.09 .45
 Factors for three-sigma control limits for and R charts
 FACTORS FOR R CHARTS Number of Observations in Subgroup,n Factor for  Chart,A2 Lower Control Limit,D3 Upper Control Limit,D4 2 1.88 0 3.27 3 1.02 0 2.57 4 0.73 0 2.28 5 0.58 0 2.11 6 0.48 0 2.00 7 0.42 0.08 1.92 8 0.37 0.14 1.86 9 0.34 0.18 1.82 10 0.31 0.22 1.78 11 0.29 0.26 1.74 12 0.27 0.28 1.72 13 0.25 0.31 1.69 14 0.24 0.33 1.67 15 0.22 0.35 1.65 16 0.21 0.36 1.64 17 0.20 0.38 1.62 18 0.19 0.39 1.61 19 0.19 0.40 1.60 20 0.18 0.41 1.59
 a. Using the factors in the above table, determine upper and lower limits for mean and range charts.(Round your intermediate calculations and final answers to 4 decimal places.)
 Upper limit for mean Lower limit for mean Upper limit for range Lower limit for range

b.

Is the process in control?

 Yes No

Problem 10-4

 Computer upgrades have a nominal time of 80 minutes. Samples of five observations each have been taken, and the results are as listed.
 SAMPLE 1 2 3 4 5 6 79.2 80.5 79.6 78.9 80.5 79.7 78.8 78.7 79.6 79.4 79.6 80.6 80.0 81.0 80.4 79.7 80.4 80.5 78.4 80.4 80.3 79.4 80.8 80.0 80.2 80.1 80.8 80.6 78.8 81.1
 Factors for three-sigma control limits for and R charts
 FACTORS FOR R CHARTS Number of Observations in Subgroup,n Factor for  Chart,A2 Lower Control Limit,D3 Upper Control Limit,D4 2 1.88 0 3.27 3 1.02 0 2.57 4 0.73 0 2.28 5 0.58 0 2.11 6 0.48 0 2.00 7 0.42 0.08 1.92 8 0.37 0.14 1.86 9 0.34 0.18 1.82 10 0.31 0.22 1.78 11 0.29 0.26 1.74 12 0.27 0.28 1.72 13 0.25 0.31 1.69 14 0.24 0.33 1.67 15 0.22 0.35 1.65 16 0.21 0.36 1.64 17 0.20 0.38 1.62 18 0.19 0.39 1.61 19 0.19 0.40 1.60 20 0.18 0.41 1.59
 a. Using factors from above table, determine upper and lower control limits for mean and range charts.(Round your intermediate calculations and final answers to 2 decimal places. Leave no cells blank - be certain to enter "0" wherever required.)
 Mean Chart Range Chart UCL LCL

b.

Decide if the process is in control.

 Yes No

Problem 10-6

 A medical facility does MRIs for sports injuries. Occasionally a test yields inconclusive results and must be repeated. Using the following sample data and n = 192.

 SAMPLE 1 2 3 4 5 6 7 8 9 10 11 12 13 Number of retests 1 1 2 0 2 1 1 0 2 9 4 2 1

 a. Determine the upper and lower control limits for the fraction of retests using two-sigma limits. (Do not round intermediate calculations. Round your final answers to 4 decimal places. Leave no cells blank - be certain to enter "0" wherever required.)

 UCL LCL

b.

Is the process in control?

 Yes No

Problem 10-7

 The postmaster of a small western town receives a certain number of complaints each day about mail delivery.
 DAY 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Number of complaints 4 12 15 8 9 6 5 13 14 7 6 4 2 10
 a. Determine two-sigma control limits using the above data. (Round your intermediate calculations to 4 decimal places and final answers to 3 decimal places. Leave no cells blank - be certain to enter "0" wherever required.)
 UCL LCL

b.

Is the process in control?

 No Yes

Problem 10-8

 Given the following data for the number of defects per spool of cable.
 OBSERVATION 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Number of defects 1 3 1 0 1 3 2 0 2 4 3 1 2 0
 a. Determine three-sigma control limits using the above data. (Do not round intermediate calculations. Round your final answers to 2 decimal places. Leave no cells blank - be certain to enter "0" wherever required.)
 UCL LCL

b.

Is the process in control?

 Yes No

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