A national manufacturer of ball bearings is experimenting with two different processes for producing precision ball bearings. It is important that the diameters be as close as possible to an industry standard. The output from each process is sampled and the average error from the industry standard is measured in millimeters. The results are presented next. The researcher is interested in determining whether there is evidence that the two processes yield different average errors. The population standard deviations are unknown but are assumed equal. This example is what type of test?
A) A one-sample test of means
B) A two-sample test of means
C) A paired t-test
D) A test of proportions

Question

A national manufacturer of ball bearings is experimenting with two different processes for producing precision ball bearings. It is important that the diameters be as close as possible to an industry standard. The output from each process is sampled and the average error from the industry standard is measured in millimeters. The results are presented next.  The researcher is interested in determining whether there is evidence that the two processes yield different average errors. The population standard deviations are unknown but are assumed equal. This example is what type of test?
A) A one-sample test of means 
B) A two-sample test of means 
C) A paired t-test 
D) A test of proportions

Quizplus · Accepted Answer

This is a two-sample test of means as there are two different processes being compared and the researcher wants to determine if they yield different average errors.

A National Manufacturer of Ball Bearings Is Experimenting with Two