Displayed below is a pair of frequency distribution containing serum cotinine levels for a group of cigarette smokers and a group of nonsmokers. These measurements were recorded as part of a study investigating various risk factors for cardiovascular disease. Cotinine Level (ng/ml)	Smokers	Nonsmokers
0-13 14-49 50-99 100-149 150-199 200-249 250-299 300+	90 125 166 320 189 213 149 469	4210 57 26 12 5 6 19 21
Total	1721	4356

a. Compare the grouped mean and grouped standard deviation of the serum cotinine level measurements for both smokers and nonsmokers. For the last interval300+ ng/ml consider the midpoint of the interval to be 340 ng/ml.

b. In which interval does the median serum cotinine level fall for smokers? For nonsmokers?

c. Compare the distribution of serum cotinine levels for smokers and nonsmokers.