# Statistics

posted by
**Angel** on
.

A manufacturer of a low-tar cigarette claims that their cigarettes contain an average of 16.3 mg of tar with a standard deviation of 3.1 mg per cigarette. How many sample cigarettes must the manufacturer observe to be 99% confident that the width of the confidence interval is 4 mg or less? Assume that the tar content of the manufactured cigarettes is normally distributed.