Problem 10-7 The postmaster of a small western town receives a certain number of

Question

Problem 10-7 The postmaster of a small western town receives a certain number of complaints each day about mail delivery. 1 2 3 4 5 6 78 910 11 12 13 14 4 11 15 896 5 12 15 7 642 11 Number of complaints 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 control limit value to zero.) certain to enter"O" wherever required. Round up any negative UCL LCL b. Is the process in control? O No O Yes

Explanation / Answer

C chart will be used

c = Total number of complaints/Total number of samples = (4+11+15+8+9+6+5+12+15+7+6+4+2+11)/14 = 8.2143

z value is 2

a) UCL = c + z*sqrt(c) = 8.2143 + 2*sqrt(8.2143) = 13.946

LCL = c - z*sqrt(c) = 8.2143 - 2*sqrt(8.2143) = 2.482

b) No

The samples of Day 3 and Day 9 are outside UCL range

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