Checkout time at a supermarket is monitored using a range and mean chart. Six samples which contain 20 observations per sample have been collected and the sample means and sample ranges have been computed as shown below:
|
Sample
|
Mean
|
Range
|
|
1
|
3.05
|
0.42
|
|
2
|
3.01
|
40.44
|
|
3
|
3.11
|
0.39
|
|
4
|
3.45
|
0.49
|
|
5
|
4.11
|
0.53
|
|
6
|
3.09
|
0.45
|
Determine the UCL and LCL for the X-Bar and the R-Chart for the sample size of 6.