Refer to the Anti-corrosion Methods and Materials (Vol. 50, 2003) study of the surface roughness of coated interior pipe used in oil fields, Exercise 7.26. The data (in micrometers) for 20 sampled pipe sections are reproduced in the table.

a. Give the null and alternative hypotheses for testing whether the mean surface roughness of coated interior pipe, m, differs from 2 micrometers.

b. The results of the test, part a, are shown in the MINITAB printout at the bottom of the page. Locate the test statistic and p-value on the printout.

c. Give the rejection region for the hypothesis test, using α = .05.

d. State the appropriate conclusion for the hypothesis test.

e. In Exercise 7.26 you found a 95% confidence interval for μ. Explain why the confidence interval and test statistic lead to the same conclusion about μ.

Data from Exercise 7.26

Refer to the Anti-corrosion Methods and Materials (Vol. 50, 2003) study of the surface roughness of coated interior pipe used in oil fields, Exercise 2.20. The data (in micrometers) for 20 sampled pipe sections are reproduced in the table on p. 312. A MINITAB analysis of the data is shown below.

Data from Exercise 2.20

Oil field pipes are internally coated in order to prevent corrosion. Engineers at the University of Louisiana, Lafayette, investigated the influence that coating may have on the surface roughness of oil field pipes (Anti-corrosion Methods and Materials, Vol. 50, 2003). A scanning probe instrument was used to measure the surface roughness of 20 sample sections of coated interior pipe.

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One-Sample T: ROUGH Test of mu = 2 vs not = 2 Variable N Mean StDev SE Mean 95% CI ROUGH 20 1.88100 0.52391 0.11715 (1.63580, 2.12 620) -1.02 0.322