4. The data below are X-bar and R values for 25 samples of size n = 4 taken from a process filling bags of fertilizer. The measurements are made on the fill weight of the bags in pounds.
Sub group number
X-bar
Range
1
50.3
0.73
2
49.6
0.75
3
50.8
0.79
4
50.9
0.74
5
49.8
0.72
6
50.5
0.73
7
50.2
0.71
8
49.9
0.70
9
50.0
0.65
10
50.1
0.67
11
50.2
0.65
12
50.5
0.67
13
50.4
0.68
14
50.8
0.70
15
50.0
0.65
16
49.9
0.66
17
50.4
0.67
18
50.5
0.68
19
50.7
0.70
20
50.2
0.65
21
49.9
0.60
22
50.1
0.64
23
49.5
0.60
24
50.0
0.62
25
50.3
0.60
Set up the X-bar and R charts on this process. Interpret the charts. Does the process seem to be in control? If necessary, assume assignable causes and revise the trial control limits. If the average fill of the bags is to be 50.0 pounds, how does this process compare?