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Unformatted text preview: the population mean is
between 10.99 and 11.00 inches. The desired mean is within this
interval and we can conclude the production process is working Example 1 Interval Estimation A paper manufacturer has a production process that operates
continuously throughout an entire production shift. The paper is
expected to have a mean length of 11 inches, and the standard
deviation of the length is 0.02 inches. At periodic intervals, a sample is
selected to determine whether the mean paper length is still equal to 11
inches or whether something has gone wrong with the production
process to change the length of the paper produced. You select a
random sample of 100 sheets, and the mean paper length is 10.998
inches. Construct a 95% and a 99% confidence interval estimate for the
population mean paper length. Comment on the functioning of the
For α=0.01
production process.
using CONFIDENCE.NORM (alpha,standard_dev,size)
lower: =10.998–CONFIDENCE.NORM
(0.01,0.02,100)=10.99284834
upper: =10.998+CONFIDENCE.NORM
(0.01,0.02,100)=11.0031516
Therefore, we are 99% confident that the population mean is between
10.9928 and 11.0032 and the process is working correctly. Example 2
One of the few negative side effects of quitting smoking is weight gain.
Suppose that the weight gain in the 12 months following a cessation in
smoking is normally distributed with a standard deviation of 6 kilograms.
To estimate the mean weight gain, a random sample of 13 quitters was
drawn their weight gains recorded and listed here. Determine the 90%
confidence interval estimate of the mean 12month weight gain for all
quitters. Interval Estimation Example 2
One of the few negative side effects of quitting smoking is weight gain.
Suppose that the weight gain in the 12 months following a cessation in
smoking is normally distributed with a standard deviation of 6 kilograms.
To estimate the mean weight gain, a random sample of 13 quitters was
drawn their weight gains recorded and listed here. Determine the 90%
confiden...
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This document was uploaded on 03/05/2014.
 Spring '13

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