A furniture manufacturer is producing cushions for
Use Excel to answer the following questions
1. A furniture manufacturer is producing cushions for their premier line of leather sofas. In order to fit in the sofas, the cushions need to be approximately 24 inches wide. The following 10 cushion samples were taken over a weeklong period.
|
Sample Number |
Inches |
|||
|
1 |
23.75 |
24.22 |
23.85 |
24.17 |
|
2 |
24.08 |
24.27 |
23.51 |
23.94 |
|
3 |
24.56 |
24.30 |
24.10 |
24.15 |
|
4 |
23.89 |
23.51 |
23.57 |
24.10 |
|
5 |
24.01 |
23.82 |
24.00 |
24.52 |
|
6 |
24.15 |
23.97 |
24.08 |
24.05 |
|
7 |
24.12 |
23.90 |
24.15 |
24.61 |
|
8 |
23.80 |
23.77 |
23.95 |
24.15 |
|
9 |
23.51 |
24.75 |
24.51 |
23.75 |
|
10 |
24.00 |
25.01 |
23.05 |
23.67 |
a. Use the two methods introduced to construct a 3-sigma x-bar chart based on the above data.
b. Use the above data to construct a 3-sigma R chart.
c. Suppose the LSL and USL are 23.5 inches and 25 inches. Compute Cpk and determine whether the process meets specification.
2. Completed forms from a particular department of an insurance company were sampled on a daily basis as a check against the quality of performance of that department. To establish a tentative norm for the department, one sample of 100 units was collected each day for 15 days:
|
Sample |
Sample Size |
Number of Forms with Errors |
|
1 |
100 |
4 |
|
2 |
100 |
3 |
|
3 |
100 |
5 |
|
4 |
100 |
0 |
|
5 |
100 |
2 |
|
6 |
100 |
8 |
|
7 |
100 |
1 |
|
8 |
100 |
3 |
|
9 |
100 |
4 |
|
10 |
100 |
2 |
|
11 |
100 |
7 |
|
12 |
100 |
2 |
|
13 |
100 |
1 |
|
14 |
100 |
3 |
|
15 |
100 |
1 |
Develop a p-chart using a 95% confidence level (z-score = 1.96)
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Solution: A furniture manufacturer is producing cushions for