It is necessary for an automobile producer to estimate the number of miles per gallon achieved by its cars. Suppose that the sample mean for a random sample of120 cars is30.1 miles and assume the standard deviation is2.5miles. Now suppose the car producer wants to test the hypothesis that, the mean number of miles per gallon, is28.5

28.5against the alternative hypothesis that it is not28.5

28.5. Conduct a test using=.05by giving the following:

(a)positive criticalz-score

(b)negative criticalzscore

(c)test statistic

The final conclusion is

A.We can reject the null hypothesis that=28.5and accept that28.5

B.There is not sufficient evidence to reject the null hypothesis that=28.5