A National Manufacturer of Ball Bearings Is Experimenting with Two

Multiple Choice

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 calculated. The results are presented below:
The researcher is interested in determining whether there is evidence that the two processes yield
Different average errors.
What is the null hypothesis?

A) µA - µB = 0
B) µA - µB ≠ 0
C) µA - µB ≤ 0
D) µA - µB > 0