Sales of Cigarettes. In the “Federal Trade Commission Cigarette Report for 2011”, it states that more than 293 billion cigarettes were purchased in the United States in 2011, with three companies selling nearly 85% of them. The tobacco industry spent

$8.4 billion on cigarette advertising and promotional expenses in the U.S. alone. The following data is the cigarettes sold in the U.S. from 1985 to 1999 (in billion). 599.3 586.4 575.4 560.7 525.6 523.7 510.9 506.4 461.4 490.2 482.3 484.1 478.6 458.6 411.3

a. Determine the quartiles for these data.

b. Remark on the usefulness of quartiles with respect to this data set.