Auto pistons are produced in a forging process, and the variability of the diameter is a critical factor that must be controlled. From five samples collected on 5 different days (one sample each day), each containing 10 pistons, the mean and the range of the diameters have been measured as follows:

Day	Mean (mm)	Range (mm)
1	154.9	4.4
2	153.2	4.8
3	151.6	4.3
4	153.5	4.8
5	156.6	4.5

Assuming the confidence level 99.73%, choose the right control chart for controlling the variability of the diameter and find its upper control limit?

Note: Enter the value of the upper control limit after rounding to two decimal places.