CHAPTER 8 EXERCISE 2, 4, 8 2. The producers of a new toothpaste claim that it prevents more cavities than other brands of toothpaste. A random sample of 60 people used the new toothpaste for 6 months. The mean number of cavities at their next checkup is 1.5. In the general population, the mean number of cavities at a 6-month checkup is 1.73 ( = 1.12). a. Is this a one- or two-tailed test? b. What are H0 and Ha for this study Z c. Compute d. What is e. Should Z obt ? Type equation here . cv? H0 be rejected? What should the researcher conclude? f. Determine the 95% confidence interval for the population mean, based on the sample mean. Henry performed a two-tailed test for an experiment in which N = 24. He could not find his t t table of t critical values, but he remembered the cv at df = 13. He decided to compare his obt with this tcv. Is he more likely to make a Type I or a Type II error in this situation? people who exercise in California is greater than the national exercise rate. The national rate is 8. A researcher believes that the percentage of people who exercise in California is greater than the national exercise rate. The national rate is 20%. The researcher gathers a random sample of 120 individuals who live in California and finds that the number who exercise regularly is 31 out of 120. a. What is b. What is c. What is X 2 df X 2 obt ? for this test? cv ? d. What conclusion should be drawn from these results? Jackson, Sherri L. (2011-03-03). Research Methods and Statistics: A Critical Thinking Approach (Page 220). Cengage Textbook. Kindle Edition. Jackson, Sherri L. (2011-03-03). Research Methods and Statistics: A Critical Thinking Approach (Page 220). Cengage Textbook. Kindle Edition