Problem:
Computer upgrades have a nominal time of 80 minutes. Samples of 10 observations each have been taken, and the results are as listed. Historical data show that the standard deviation of the upgrade times is 0.5 minutes.
|
|
Sample 1
|
Sample 2
|
Sample 3
|
Sample 4
|
Sample 5
|
|
Observation 1
|
79.2
|
80.5
|
79.6
|
78.9
|
79.7
|
|
Observation 2
|
78.8
|
78.7
|
79.6
|
79.4
|
80.6
|
|
Observation 3
|
80.0
|
81.0
|
80.4
|
79.7
|
80.5
|
|
Observation 4
|
78.4
|
80.4
|
80.3
|
79.4
|
80.0
|
|
Observation 5
|
81.0
|
80.1
|
80.8
|
80.6
|
81.1
|
|
Observation 6
|
77.8
|
78.8
|
80.4
|
77.7
|
79.8
|
|
Observation 7
|
79.3
|
79.6
|
79.4
|
80.6
|
81.0
|
|
Observation 8
|
80.4
|
80.5
|
78.7
|
80.8
|
80.6
|
|
Observation 9
|
81.1
|
79.4
|
81.3
|
81.0
|
80.8
|
|
Observation 10
|
80.9
|
80.2
|
80.5
|
79.2
|
77.9
|
|
Sample Mean, X-bar
|
79.69
|
79.92
|
80.1
|
79.73
|
80.20
|
|
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Required:
Question 1) What are the 3-sigma (z= 3) control limits to be used in the mean (X-bar) control chart and what is the decision based on this X-bar chart?
A)
B)
C)
D)
Solve the problem and show all work.