# Z-Test for Mean, Z-Test for Proportion, ANOVA

Exercises 6 (Ch. 10) ,pg 344 - The MacBurger restaurant chain claims that the mean waiting time of customers is 3 minutes with a population standard deviation of 1 minute. The quality-assurance department found in a sample of 50 customers at the Warren Road MacBurger that the mean waiting time was 2.75 minutes. At the .05 significance level, can we conclude that the mean waiting time is less than 3 minutes?

Exercises 28 (Ch. 11), pg 397 - Each month the National Association of Purchasing Managers publishes the NAPM index. One of the questions asked on the survey to purchasing agents is: Do you think the economy is expanding? Last month, of the 300 responses, 160 answered yes to the question. This month, 170 of the 290 responses indicated they felt the economy was expanding. At the .05 significance level, can we conclude that a larger proportion of the agents believe the economy is expanding this month?

Exercises 34 (Ch. 12), pg 442 There are four auto body shops in Bangor, Maine, and all claim to promptly serve customers. To check if there is any difference in service, customers are randomly selected from each repair shop and their waiting times in days are recorded. The output from a statistical software package is:

Summary

Groups Count Sum Average Variance

Body Shop A 3 15.4 5.133333 0.323333

Body Shop B 4 32 8 1.433333

Body Shop C 5 25.2 5.04 0.748

Body Shop D 4 25.9 6.475 0.595833

ANOVA

Source SS df MS F p-value

Between Groups 23.37321 3 7.791069 9.612506 0.001632

Within Groups 9.726167 12 0.810514

Total 33.09938 15

Is there evidence to suggest a difference in the mean waiting times at the four body

shops? Use the .05 significance level.

Exercises 26 (Ch. 17), pg 665

26. A study regarding the relationship between age and the amount of pressure sales personnel feel in relation to their jobs revealed the following sample information. At the .01 significance level, is there a relationship between job pressure and age?

Degree of Job Pressure

Age (years) Low Medium High

Less than 25 20 18 22

25 up to 40 50 46 44

40 up to 60 58 63 59

60 and older 34 43 43

https://brainmass.com/statistics/analysis-of-variance/z-test-for-mean-z-test-for-proportion-anova-327342

#### Solution Summary

The solution provides step-by-step method of performing Z-test for Mean, Z-Test for Proportion and ANOVA. All the steps of hypothesis testing (formulation of null and alternate hypotheses, selection of significance level, choosing the appropriate test-statistic, decision rule, calculation of test-statistic and conclusion) have been explained in details. A separate Excel sheet showing the ANOVA analysis has also been included.