SOLUTION: As a structure’s engineer at Ford, if one of my parts was out of spec we wouldn’t be able to build the car because everything attaches to the sheet metal. To ensure that our parts

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Question 315034: As a structure’s engineer at Ford, if one of my parts was out of spec we wouldn’t be able to build the car because everything attaches to the sheet metal. To ensure that our parts were being built correctly, we would take random measurements and a sample of these measurements is shown in the attached graph. This data is actually 50 measurements of a hole’s diameter where the Instrument Panel attaches. The hole is supposed to have a diameter of 8 +/- 0.2 mm. What observations and conclusions can you make from this data? Make sure to show any/all work and feel free to use the spreadsheet to perform any calculations.
50 random sample measurements (mm)
8
8.2
8.4
8.5
8.1
8
8.5
8.4
8.4
8.9
8.3
7.9
8.3
8.3
8.3
8.0
8.3
8.0
8.3
8.1
7.9
8.1
8.1
8.1
8.8
8.1
8.1
8.0
8.2
7.9
8.1
8.0
8.2
8.2
8.2
8.1
7.9
8.3
8.3
8.3
8.2
8.2
8.2
8.1
9.0
8.8
8.8
9.0
8.9
8.8

Measurement (mm) Number of samples at that measurement
7.9 4
8 6
8.1 10
8.2 8
8.3 9
8.4 3
8.5 2
8.8 4
8.9 2
9 2



Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
The average of the data is 8.282 with a standard deviation of 0.301.
The upper acceptable limit is 8.2.
The lower acceptable limi is 7.8.
This process is badly out of control.
Not only is the average above the upper limit but the spread of the data is too wide.
You would want the (Ave-3*sigma, A+3*sigma) to be contained within the (7.8-8.2) allowable range.
With this process, (Ave-3*sigma, A+3*sigma)=(7.4-9.2) nowhere near the current allowable limits.
Stop this process and fix whatever is broken.