Given the following data, construct a three-sigma range control
chart.
| Day of Sample | Sample Values |
| Saturday | 22,19,20 |
| Sunday | 21,20,17 |
| Monday | 16,17,18 |
| Tuesday | 20,16,21 |
| Wednesday | 23,20,20 |
| Thursday | 19,16,21 |
a. If Friday’s results are 15,14,21 is the process in
control?
b.Construct a three-sigma means control chart and determine if
the process is still in control on Friday.





