Question

A tire manufacturer claims that the average life of a certain grade of tire is 50,000 miles or more when used under normal driving conditions. A random sample of 20 tires is selected and tested and the sample mean is 49,650 miles. Assume the population of the lives is to be normal with standard deviation of 5,000 miles. At the 5% significance level, the manufacturer’s claim is tested. What is the decision rule in this test?

Select one:

A. Reject H₀ if Z_STAT < –1.645; otherwise, do not reject H₀.

B. Reject H₀ if t_STAT < –2.0930 or t_STAT > +2.0930; otherwise, do not reject H₀.

C. Reject H₀ if Z_STAT > +1.96; otherwise, do not reject H₀.

D. Reject H₀ if t_STAT > –1.7291; otherwise, do not reject H₀.

Answer 1