Quasar Exports Ltd, a fictional Turkish manufacturer of glass, wants to use a c chart to monitor the number of defects in the sheets of glass it produces. The company wants to use the chart to address the production problems it is experiencing and use it on an ongoing basis as a monitoring tool. To construct the chart, the company collected data over 5 days by inspecting 30 sheets of glass and recording the number defects per sheet. The data are as follows:

1. Why did the company choose a c-chart to monitor this process?

2. Using the data in the table, construct a c-chart using 3σ control limits.

3. After making quality improvements to the process and concluding that it is in control in the current week, the quality control manager of Quasar collected data on the number of defects per sheet for the following week using 20 glass sheets. The defects per sheet were as follows: 2, 7, 4, 5, 6, 4, 8, 1, 5, 3, 4, 4, 7, 2, 8, 3, 5, 6, 4, and 3.

Plot the data on the c-chart, and determine whether the process is in control.

Transcribed Image Text:

Defects per Sheet Defects per Sheet Defects per Sheet Sample Sample 11 Sample 21 11 12 22 12 3 13 23 12 24 4 14 11 25 14 15 6. 14 16 26 3 17 9. 27 13 28 18 10 19 29 9. 6. 4. 10 20 30