A process considered to be in control measures an ingredient inounces. A quality inspector took 10 samples, each with 5observations as follows:
Samples | Observations |
1 | 2 | 3 | 4 | 5 |
1 | 10 | 9 | 10 | 9 | 12 |
2 | 9 | 9 | 11 | 11 | 10 |
3 | 13 | 9 | 10 | 10 | 9 |
4 | 10 | 10 | 11 | 10 | 10 |
5 | 12 | 10 | 9 | 11 | 10 |
6 | 10 | 10 | 8 | 12 | 9 |
7 | 10 | 11 | 10 | 8 | 9 |
8 | 13 | 10 | 8 | 10 | 8 |
9 | 8 | 8 | 12 | 12 | 9 |
10 | 10 | 12 | 9 | 8 | 12 |
a) Using this information, obtain three-sigma (i.e., z=3)control limits for a mean control chart and control limits for arange chart, respectively. It is known from previous experiencethat the standard deviation of the process is 1.36.
b) Discuss whether the process is in control or not.
