3. To help consumers assess the risks they are taking, the Food and Drug Administration (FDA) publishes the amount of tar found in all brands of cigarettes.  For a particular brand of cigarette, FDA tests yielded a mean tar level of 1.89 milligrams and standard deviation of 0.4 milligrams for a sample of nine cigarettes. Construct a 99% confidence interval for the mean tar content of this brand of cigarette.