X-Chart and P-Chart

PROBLEMS
2. Control charts for X and R are to be established on a certain dimension part, measured in millimeters. Data were collected in subgroup sizes of 6 and are given below. Determine the trial central line and control limits. Assume assignable causes and revise the central line and limits.

|SUBGROUP NUMBER |Xbar |R |SUBGROUP NUMBER |Xbar |R |
| |20.35 |0.34 | 14. |20.41 |0.36 |
| |20.40 |0.36 | 15. |20.45 |0.34 |
| |20.36 |0.32 |16. |20.34 |0.36 |
| |20.65 |0.36 |17. |20.36 |0.37 |
| |20.20 |0.36 |18. |20.42 |0.73 |
| |20.40 |0.35 |19. |20.50 |0.38 |
| |20.43 |0.31 |20. |20.31 |0.35 |
| |20.37 |0.34 |21. |20.39 |0.38 |
| |20.48 |0.30 |22. |20.39 |0.33 |
| |20.42 |0.37 |23. |20.40 |0.32 |
| |20.39 |0.29 |24. |20.41 |0.34 |
| |20.38 |0.30 |25.