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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
At 95% confidence level, zα/2 = z.025 = 1.960
production process.
Interval estimate:
x ± zα 2 σn
.02
10.998 ±1.960 0100 10.998 ± 0.00392
10.99408 ≤ µ ≤11.00192
With 95% confidence, we conclude that 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=0.05
production process.
using CONFIDENCE.NORM(alpha,standard_dev,size)
lower: =10.998–
CONFIDENCE.NORM(0.05,0.02,100)=10.99408007
upper:
=10.998+CONFIDENCE.NORM(0.05,0.02,100)=11.00191993
Therefore, we are 95% confident that the population mean is between
10.9941 and 11.0019 and the process is working correctly. 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...
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This document was uploaded on 03/05/2014.
 Spring '13

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