22. Fifteen years ago, a complete survey of all undergraduate students at a large university 22.

indicated that the average student smoked X 8 3 cigarettes per day. The director of the student health center wishes to determine whether the incidence of cigarette smoking at his university has decreased over the 15-year period. He obtains the following results (in cigarettes smoked per day) from a recently selected random sample of undergraduate students:X 4 6, s 3 2, n 100.

(a) Set up H0 and H1.

(b) Perform the statistical test (α 05).

(c) Draw the final conclusions.