Test 4

7.

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 0.006 inch. After recalibrating the production​ machine, the manager randomly selects 29 pistons and determines that the standard deviation is 0.0051 inch. Is there significant evidence for the manager to conclude that the standard deviation has decreased at the á=0.01 level of​ significance?

What are the correct hypotheses for this​ test?

The null hypothesis is H0​:

The alternative hypothesis is H1

Calculate the value of the test statistic.

Use technology to determine the​ P-value for the test statistic.

The​ P-value is

What is the correct conclusion at the

á=0.01

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 0.01 level of significance.