FTC cigarette rankings
Periodically, the Federal Trade Commission (FTC) ranks domestic cigarette brands according to tar, nicotine, and carbon monoxide content. The test results are obtained by using a sequential smoking machine to ‘‘smoke'' cigarettes to a 23-millimeter butt length. The tar, nicotine, and carbon monoxide concentrations (rounded to the nearest milligram) in the residual ‘‘dry'' particulate matter of the smoke are then measured. The accompanying SAS printouts describe the nicotine contents of 500 cigarette brands. (The data are saved in the FTC file.)
(a) Examine the relative frequency histogram for nicotine content. Use the rule of thumb to describe the data set
(b) Locate y‾ and s on the printout, then compute the interval y‾ ± 2x.
(c) Based on your answer to part a, estimate the percentage of cigarettes with nicotine contents in the interval formed in part b.
(d) Use the information on the SAS histogram to determine the actual percentage of nicotine contents that fall within the interval formed in part b. Does your answer agree with your estimate of part c?
