An article published in the Journal of the American MedicalAssociation (Oct. 16,1995) calls smoking in China

"a public health emergency." The researchers found that smokers in China smoke an average of 16.5 cigarettes a day.The high smoking rate is one reason why the tobacco industry is the central government's largest source of tax revenue. Has the average number of cigarettes smoked per day by Chinese smokers increased over the past two years? Consider that in a random sample of 200 Chinese smokers in 1997, the number of cigarettes smoked per day had a mean of 17.05 and a standard deviation of 5.21.

a. Set up the null and alternative hypotheses for testing whether Chinese smokers smoke, on average, more cigarettes a day in 1997 than in 1995. (Assume that the population mean for 1995 is p = 16.5.)

b. Compute and interpret the observed significance level of the test.

c. Why is a two-tailed test inappropriate for this problem?