An 80 kg man is put into a tank of water. When completely submerged he displaces
75 L of water. If fatty body tissue has an average density of 0.9 kg/L and non-fatty body tissue
has an average density of 1.1 kg/L, what percentage of the man is composed of fat?
volume of man = 75 liters
so density of man = 80 kg/75 L = 1.067 kg/L
x(fat density ) + (1-x)(bone density) = 1.067
.9 x + 1.1 (1-x) = 1.067
1.1 - 1.067 = (1.1-.9)x
x = .167 or 17%