The piston diameter of a certain hand pump is 0.6 inch. The manager determines that the diameters are normally​ distributed, with a mean of 0.6 inch and a standard deviation of 0.005 inch. After recalibrating the production​ machine, the manager randomly selects 21 pistons and determines that the standard deviation is 0.0044 inch. Is there significant evidence for the manager to conclude that the standard deviation has decreased at the α=0.05 level of​ significance?

Calculus For The Life Sciences
2nd Edition
ISBN:9780321964038
Author:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Publisher:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Chapter13: Probability And Calculus
Section13.2: Expected Value And Variance Of Continuous Random Variables
Problem 10E
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8.20 The piston diameter of a certain hand pump is 0.6 inch. The manager determines that the diameters are normally​ distributed, with a mean of 0.6 inch and a standard deviation of 0.005 inch. After recalibrating the production​ machine, the manager randomly selects 21 pistons and determines that the standard deviation is 0.0044 inch. Is there significant evidence for the manager to conclude that the standard deviation has decreased at the α=0.05 level of​ significance?

What are the correct hypotheses for this test?
The null hypothesis is H
The alternative hypothesis is H
Calculate the value of the test statistic
x² (Round to three decimal places as needed.)
Use technology to determine the P-value for the test statistic
The P-value is
(Round to three decimal places as needed.)
What is the correct conclusion at the a=0.10 level of significance?
Since the P-value is
than the level of significance,
the null hypothesis. There
sufficient evidence to conclude that the standard deviation has decreased at the 0.10 level of significance.
Transcribed Image Text:What are the correct hypotheses for this test? The null hypothesis is H The alternative hypothesis is H Calculate the value of the test statistic x² (Round to three decimal places as needed.) Use technology to determine the P-value for the test statistic The P-value is (Round to three decimal places as needed.) What is the correct conclusion at the a=0.10 level of significance? Since the P-value is than the level of significance, the null hypothesis. There sufficient evidence to conclude that the standard deviation has decreased at the 0.10 level of significance.
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ISBN:
9780321964038
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GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Publisher:
Pearson Addison Wesley,