The owner of a fast-food restaurant has found the daily demand for ground beef at her restaurant to be normally distributed, with a mean of 680 lb and a standard deviation of 80 lb. Since the fast-food business is very competitive, the manager would like to ensure that sufficient ground beef is available in her restaurant each day so that the probability is no greater than 2% that the day's supply is exhausted. How many pounds of ground beef should the manager have available for use each day?