"Tar" is the term used to describe the toxic chemicals found in cigarettes. The con- centration of tar in a cigarette determines its rating: High-tar cigarettes contain at least 22 milligrams (mg) of tar; medium-tar cigarettes from 15 mg to 21 mg; and low-tar cigarettes 7 mg or less of tar. In Canada, tobacco companies are currently required by law to print the levels of tar, nicotine, carbon monoxide, hydrogen cyanide, formalde- hyde, and benzene in smoke from their cigarettes." From a particular Canadian brand, 10 cigarettes were randomly selected and the content of tar (in mg) was measured. The results were 13.5, 14.0, 13.9, 14.2, 15.1, 14.6, 13.8, 14.0, 14.1, and 14.7 mg per cigarette. Assume these measurements were taken from a population with a normal distribution. Construct a 90% confidence interval for the mean tar content of any cigarette of this brand.