One of the most accurate means of determining the fat content of a person is by measuring their specific gravity. It is a complementary component of one's body-mass-index (BMI). The measurement is made by immersing the person in a tank of water and measuring his net weight. Derive an expression for a person's specific gravity in terms of their weight in air, net weight in water, and specific gravity of the water. Find values for the density of fat and muscle to develop your correlation. Is there anything you might have left out of the analysis that would affect your results?