# Test of Hypothesis

Use the following to answer questions 1-6.:

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 12 14

The researcher is interested in determining whether there is evidence that the two processes yield different average errors.

1. What is the null hypothesis?

A)

B)

C)

D)

2. What is the alternate hypothesis?

A)

B)

C)

D)

3. What is the degrees of freedom?

A) 10

B) 13

C) 26

D) 24

4. What is the critical t value at the 1% level of significance?

A) +2.779

B) -2.492

C) 1.711

D) 2.797

5. Assume calculated t to be +2.70, at the 0.01 level of significance what would be the decision?

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

B) Reject the null hypothesis and conclude the means are the same.

C) Fail to reject the null hypothesis and conclude the means are the same.

D) Fail to reject the null hypothesis and conclude the means are different.

6. This example is what type of test?

A) One sample test of means.

B) Two sample test of means.

C) Paired t-test.

D) Test of proportions.

#### Solution Preview

The answers are in attached file:

Use the following to answer questions 1-6.:

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 ...

#### Solution Summary

Answers questions on test of hypothesis.