Cigarettes Some of the cigarettes sold in the US claim to be “low tar”. How much less tar would a smoker get by smoking low tar brands instead of regular cigarettes? Samples of 15 brands of each type were randomly chosen from the 1206 varieties (no kidding) that are marketed. Their tar contents (mg/cig) are listed in the table below. Find a 95 % confidence interval for the difference between regular and low tar brands. Type Milligrams of tar per cigarette Regular 18 10 14 15 15 12 17 11 14 17 12 14 15 15 12 Low Tar 9 5 10 4 8 9 9 3 7 12 6 10 8 11 8