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Efficacy of e-Cigs Do electronic cigarettes assist in helping individuals quit smoking? Researchers found 300 current smokers to volunteer for a study in which each was randomly assigned to one of three treatment groups. Group 1 received an electronic cigarette (e-cig) in which each cartridge contained 7.2 mg of nicotine, Group 2 received an e-cig that contained 5.4 mg of nicotine, and Group 3 received an e-cig that contained no nicotine. The subjects did not know which group they were assigned. During the course of the 52-week intervention, subjects dropped out of the study. At the end of the study 65 subjects remained in Group 1, 63 in Group 2, and 55 in Group 3. After 52 weeks, it was determined via questionnaire whether the subject quit smoking entirely. Results of the study are presented in the following table.

(a) What type of experimental design was used in this study?

(b) Researchers wanted to know whether electronic cigarettes may be used to help individuals abstain from cigarette smoking. What is the response variable? Is it qualitative or quantitative?

(c) To what population do the results of this study apply?

(d) State the null and alternative hypotheses.

(e) Does the evidence suggest e-cigs are effective in helping individuals abstain from cigarette smoking?

(f) Draw a conditional bar graph by group. Explain what the graph suggests.

(g) Write a conclusion for this hypothesis test.