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 calculated. The results are presented below.

	Process A	Process B
Mean	0.002mm	0.0026mm
Standard Deviation	0.0001mm	0.00012mm
Sample Size	25	12

The researcher is interested in determining whether there is evidence that the two processes yield different average errors. Assume that the population standard deviations are equal.

What is the degrees of freedom?

a.) 34

b.) 36

c.) 35

d.) 37

Answer 1

degrees of freedom = 35