Statistical Quality Control Sample Assignment
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Item _____________Number of __________ ______Item __________________Number of
Number_________Non conformaces____________Number_____________Nonconformances
1_____________ 2_____________ 14_______________ 2
2_____________ 0_____________ 15_______________ 1
3_____________ 3_____________ 16_______________ 4
4_____________ 1_____________ 17_______________ 0
5_____________ 2_____________ 18_______________ 2
6_____________ 5_____________ 19_______________ 3
7_____________ 3_____________ 20_______________ 2
8_____________ 2_____________ 21_______________ 1
9_____________ 0_____________ 22_______________ 3
10____________ 0_____________ 23_______________ 2
11____________ 4_____________ 24_______________ 0
12____________ 3_____________ 25_______________ 3
13____________ 2
______________________________________________________________________
Solution: -
Determine the cnetreline, UCL, and LCL.
Centerline = c = 2 + 0 + 3 + … + 3 = 50 = 2.0
_____________25____ 25
UCL = c + 3√c = 2.0 + 3√2.0 = 2.0 +4.2 = 6.2
LCL = c – 3√c = 2.0 – 3√2.0 = 2.0 – 4.2 = - 2.2
The lower control limit cannot be less than zero; thus, the LCL is 0. The graph of the control chart, followed by the MINITAB c chart, is shown next. Not that none of the points are beyond the control limits and there is a healthy deviation of points both above and below the centerline. This chart indicates a process that is relatively in control, with an average of two nonconformances per item.
Statistical Quality Control Sample Assignment
Questions: - A manufacture produces gauges to measure oil pressure. As part of the company’s statistical process control, 25 gauges are randomly selected and tested for nonconformance. The results are shown here. Use these data to construct a c chart that displays the nonconformance per item.Item _____________Number of __________ ______Item __________________Number of
Number_________Non conformaces____________Number_____________Nonconformances
1_____________ 2_____________ 14_______________ 2
2_____________ 0_____________ 15_______________ 1
3_____________ 3_____________ 16_______________ 4
4_____________ 1_____________ 17_______________ 0
5_____________ 2_____________ 18_______________ 2
6_____________ 5_____________ 19_______________ 3
7_____________ 3_____________ 20_______________ 2
8_____________ 2_____________ 21_______________ 1
9_____________ 0_____________ 22_______________ 3
10____________ 0_____________ 23_______________ 2
11____________ 4_____________ 24_______________ 0
12____________ 3_____________ 25_______________ 3
13____________ 2
______________________________________________________________________
Solution: -
Determine the cnetreline, UCL, and LCL.
Centerline = c = 2 + 0 + 3 + … + 3 = 50 = 2.0
_____________25____ 25
UCL = c + 3√c = 2.0 + 3√2.0 = 2.0 +4.2 = 6.2
LCL = c – 3√c = 2.0 – 3√2.0 = 2.0 – 4.2 = - 2.2
The lower control limit cannot be less than zero; thus, the LCL is 0. The graph of the control chart, followed by the MINITAB c chart, is shown next. Not that none of the points are beyond the control limits and there is a healthy deviation of points both above and below the centerline. This chart indicates a process that is relatively in control, with an average of two nonconformances per item.
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