Animals and people that take in more energy than they expend will get fatter. Here are data on 12 rhesus monkeys: 6 lean monkeys (4% to 9% body fat) and 6 obese monkeys (13% to 14% body fat). The data report the energy expended in 24 hours (kilojoules per minute) and the lean body mass (kilograms, leaving out fat) for each monkey.
Lean Obese
Body Mass Energy Body Mass Energy
6 1.13 8 0.96
7.5 1.07 9.1 1.43
9.2 1.47 10.3 1.11
9.7 1.68 12 1.4
9.1 1.08 11.9 1.27
9.1 1.18 11.2 1.37
(a) What is the mean lean body mass of the lean monkeys?
(b) What is the mean lean body mass of the obese monkeys?