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.

Process A Process B
Sample mean 2.0 3.0
Standard deviation 1.0 0.5
Sample size 12 14

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. If What is the decision if we use 1% level of significance?

a. Fail to reject the null hypothesis and conclude the means are different.
b. Reject the null hypothesis and conclude the means are different.
c. Fail to reject the null hypothesis and conclude the means are the same.
d. Reject the null hypothesis and conclude the means are the same.

Answer 1

b). Reject the null hypothesis and conclude the means are different.

Explanation:

A hypothesis is characterized as null when the data/statistics display that there is no distinction between the particular features of the groups. As per the details provided, the decision would be to 'reject/deny the null hypothesis and deduce that the means of the processes are different.' This shows that there is no association among the variables due to the distinction in the means of the two processes and other data provided. Thus, option b is the correct answer.