Chapter 9.4, Problem 8BSC

In Exercises 5–16, test the given claim.

8. Second-Hand Smoke Data Set 12 “Passive and Active Smoke” includes cotinine levels measured in a group of smokers (n = 40, $\bar{x}$ = 172.48 ng/mL, s = 119.50 ng/mL) and a group of nonsmokers not exposed to tobacco smoke (n = 40, $\bar{x}$ = 16.35 ng/mL, s = 62.53 ng/mL). Cotinine is a metabolite of nicotine, meaning that when nicotine is absorbed by the body, cotinine is produced.

a. Use a 0.05 significance level to test the claim that the variation of cotinine in smokers is greater than the variation of cotinine in nonsmokers not exposed to tobacco smoke.

b. The 40 cotinine measurements from the nonsmoking group consist of these values (all in ng/mL): 1, 1, 90, 244, 309, and 35 other values that are all 0. Does this sample appear to be from a normally distributed population? If not, how are the results from part (a) affected?