Vol. 9, No. 10

October 2007

PQ Systems

New 2008 training schedule

Quality Quiz: With a video!

Data in everyday life

MSA with Jackie Graham

Bytes and pieces

FYI: Current releases


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Quality Quiz:

Armand A. Legge learned last month how to build a confidence interval around the mean of a sample. Quality manager Al Aboard selected a sample of 36 bottles of the company’s new window-cleaning miracle. The sample showed:


Using this data, Armand built a 95% confidence mean, using the following formula:

Since it is important not only that the bottles are predictably full, but that the labels do not fall off, Armand asked Al to inspect the last 1,000 bottles to determine the rate at which labels slipped off, and discovered that 20 bottles were produced with missing labels. Armand offers to build a confidence interval for the proportion of bottles with missing labels, using the same formula:

Now it’s your turn. Is Armand’s approach to analyzing this problem the correct one?

a) Yes.

b) No.


Click here for a more complete video explanation

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