Hypothesis testing: z tests. Cereal is sold on the basis of weight, not volume.

Hypothesis testing: z tests. Cereal is sold on the basis of weight, not volume. A test of products shipped from the manufacturer found a sample average product weight of 15.9 ounces per box with a sample standard deviation of 0.1 ounces, when a sample of n=100 observations was studied.
Calculate the range within which the population average volume can be found with 99% confidence. Assuming that s=0.1 ounces cannot be reduced, and a sample size of n=100, what is the minimum range within which the sample average weight must be found to justify with 99% confidence the advertised weight of 16 oz? Is the company justified in claiming an advertised product weight of 16 oz?