6. Smoking and Blood Pressure To study the effect of smoking on blood pressure, the blood pressure of a group of 35 cigarette smokers was measured at the beginning of an experiment and again 5 years later. The sample mean increase, measured in millimeters of mercury, was x 59.7, and the sample standard deviation was s55.8.

a. Estimate the mean increase in blood pressure for cigarette smokers over the time span indicated by the experiment and find the margin of error.

b. Describe the population associated with the mean that you have estimated.

c. Using a confidence coefficient equal to .90, place a confidence interval on the mean increase in blood pressure.