Two assembly lines making the same item are monitored, one with an X-bar chart and s chart combination and the other with an X-bar chart and R chart combination. The first assembly line has =108.4 and =2.21 based on subgroups of size 4. The second assembly line has =109.2 and =4.19 based on subgroups of size 5.
1) Which assembly line exhibits more consistency (less spread)? Support your answer statistically.
2) Calculate the control limits for the X-bar and s chart for assembly line 1.
3) Calculate the control limits for the X-bar and R chart for assembly line 2.