Thermostats are subjected to rigorous testing before they are shipped to air conditioning technicians around the world. Results from the last five samples are shown in the table. Draw and R Chart and an x-bar chart. Based on the charts, is the process under control?
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|
Observations
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|
Sample
|
1
|
2
|
3
|
4
|
5
|
|
1
|
73.5
|
70.8
|
72.2
|
73.6
|
71.0
|
|
2
|
71.3
|
71.0
|
73.1
|
72.7
|
72.2
|
|
3
|
70.0
|
72.6
|
71.9
|
72.4
|
73.3
|
|
4
|
71.1
|
70.6
|
70.3
|
74.2
|
73.6
|
|
5
|
70.8
|
70.7
|
70.7
|
73.5
|
71.1
|