Fifteen years ago, a complete survey of all undergraduate students at a large university indicated that the average student smoked 6.9 cigarettes per day. The director of the student health center...

Fifteen years ago, a complete survey of all undergraduate students at a large university indicated that the average student smoked 6.9 cigarettes per day.  The director of the student health center wishes to determine whether the incidence of cigarette smoking has lessened over the 15 year period.  He takes a random sample of 13 undergraduate students and finds the following cigarettes smoked per day:  6.2, 7.1, 7.3, 6.8, 6.6, 7, 7.5, 6.8, 6.4, 6.5, 7.1, 7.3 and 6.8.  Test the null hypothesis at the .01 level of significance.