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.

1. Process A has a sample mean of 2.0, a sample standard deviation of 1.0 and a sample size of 12.

   Process B has a sample mean of 3.0, a sample standard deviation of 0.5 and a sample size of 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 assumed equal.

   What is the null hypothesis?

   H₀: _{A B}

   H₀: _A> _B

   H₀: _{A B}

   H₀: _A= _B

What is the alternative hypothesis?

1. H₁: _{A B}

   H₁: _{A B}

   H₁: _A= _B

   H₁: _A> _B

2. What test statistic should you use?

   Z score

   p-value

   t statistic

   F distribution

1. What is the critical value of the test statistic? (write down the absolute value)

1. What is the computed value of the test statistic? (report the absolute value)

1. 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 has a sample mean of 2.0, a sample standard deviation of 1.0 and a sample size of 12.

   Process B has a sample mean of 3.0, a sample standard deviation of 0.5 and a sample size of 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 assumed equal. Using a 0.01 significance level:

   Reject the null hypothesis

   Fail to reject the null hypothesis

   Reject the alternative hypothesis

   Fail to reject the alternative hypothesis.