Chapter 8.3, Problem 7E

For Exercises 7 through 23, perform each of the following steps.

a. State the hypotheses and identify the claim.

b. Find the critical value(s).

c. Find the test value.

d. Make the decision.

e. Summarize the results.

Use the traditional method of hypothesis testing unless otherwise specified.

Assume that the population is approximately normally distributed.

7. Cigarette Smoking A researcher found that a cigarette smoker smokes on average 31 cigarettes a day. She feels that this average is too high. She selected a random sample of 10 smokers and found that the mean number of cigarettes they smoked per day was 28. The sample standard deviation was 2.7. At α = 0.05 is there enough evidence to support her claim?