Question

Surface roughness of pipe. Refer to the Anti-corrosion Methods and Materials (Vol. 50, 2003) study of the sur- face roughness of coated interior pipe used in oil fields, Exercise 7.26 (p. 311). The data (in micrometers) for 20 sampled pipe sections are reproduced in the table on p. 391.

a. Give the null and alternative hypotheses for testing whether the mean surface roughness of coated interior pipe, H, 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.

Answer 1

The minitab report isn't given.

Answer:

H0 : μ = 2 um

H1 : μ ≠ 2 um

Explanation:

The mean surface roughness of coated interior pipe is given as 2um.

This refers to the population mean, μ = 2 um

Therefore, the null hypothesis which usually aligns with the population mean value will be stated as :

H0 : μ = 2 um

The alternative hypothesis is used to test the claim that the mean surface roughness is different from 2 ; hence no direction is given, this is thus a 2 - tailed test

H1 : μ ≠ 2 um