A researcher predicts that smoking cigarettes decreases a person’s sense of smell. On a test of olfactory sensitivity, the µ for nonsmokers is 18.4. A sample of people who smoke a pack a day produces these scores:
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(a) What are H0 and Ha for this study?
(b) Compute tobt.
(c) With a = .05, what is tcrit?
(d) What should the researcher conclude about this relationship?
(e) Compute the confidence interval for µ.