8.81 Less Red Meat! Canadians are becoming more conscious of the importance of good nutrition, and some researchers believe that we may be altering our diets to include less red meat and more fruits and vegetables. To test this theory, a researcher decides to select hospital nutritional records for subjects surveyed 10 years ago and to compare the average amount of beef consumed per year to the amounts consumed by an equal number of subjects she will interview this year. She knows that the amount of beef consumed annually by Canadians ranges from 0 to approximately 47 kg. How many subjects should the researcher select for each group if she wishes to esti- mate the difference in the average annual per-capita beef consumption correct to within 2.3 kg with 99% confidence?