Organic Grains LLC uses statistical process control to ensure that its health-conscious, low-fat, multigrain sandwich loaves have the proper weight. Based on a previously stable and in-control process, the control limits of the x--and R-charts are UCLx^- = 6.56. LCLx^- = 5.84, UCLR^- = 1.141, LCLR^- = 0. Over the past few days, they have taken five random samples of four loaves each and have found the following:
|
SAMPLE
|
NET WEIGHT
|
|
LOAF #1
|
LOAF #2
|
LOAF #3
|
LOAF #4
|
|
1
|
6.3
|
6.0
|
5.9
|
5.9
|
|
2
|
6.0
|
6.0
|
6.3
|
5.9
|
|
3
|
6.3
|
4.8
|
5.6
|
5.2
|
|
4
|
6.2
|
6.0
|
6.2
|
5.9
|
|
5
|
6.5
|
6.6
|
6.5
|
6.9
|
Is the process still in control? Explain why or why not.