Can someone help me on my Statistic Homework?

the meat department of a local supermarket packages ground beef using meat trays of two sizes: one designed to hold approximately 1.5 pounds of meat, and one that holds approximately 3 pounds. A random sample of 36 packages in the smaller meat trays produced weight measurements with an average of 1.51 pounds and a standard deviation of .20 pounds. Construct a 99% confidence interval for the average weight of all packages sold in the small meat trays by this supermarket chain.