As energy-storage substances, carbohydrates produce about 4 kilocalories of energy per gram, whereas fats produce about 9 kilocalories of energy per gram. The American black bear hibernates for as long as seven months in the winter, during which it does not eat.

Before hibernating, black bears put on a lot of weight, often spending 20 hours a day eating and storing as much as 50 kilograms of fat. Show that the bear would have to gain 112.5 kilograms if it stored energy as carbohydrate instead of as fat.