The supervisor of the packaging line in a shampoo manufacturer was measuring the quantity of shampoo (in ml) filled in sachets. He was interested in setting up a control chart for that stage. He took 5 samples, each with six observations and the mean and range for each sample are shown in the table below:
|
Sample No. |
|
|
|
|
|
|
Sample Mean |
2.18 |
2.12 |
1.86 |
1.98 |
2.02 |
|
Sample Range |
0.33 |
0.38 |
0.4 |
0.38 |
0.35 |
- Which type of control chart (in general and specific) should be used to monitor this situation? Why?
- Calculate the 1-sigma and 3-sigma limits.
- Draw the control chart and infer about the packaging process.
For the 1s control limits, what is the probability of concluding that the process is out of control when it is really in control?
