Q. What is the estimated percentage (in mass) of water in the human body? Is this percentage expected to be larger in the adult or in the old individual?
Ans.
Approximately 65% of the human individual mass is water. The brain, for example, has around 90% of water in mass, the muscles, 85%, and the bones have between 25% and 40% of water.
Younger adult individuals have proportionally more water in mass than older individuals.