posted by Mack .
A runner weighs 560 N (about 130 lb), and 74% of this weight is water.
(a) How many moles of water are in the runner's body?
(b) How many water molecules (H2O) are there?
runner's mass = 560N/g = 560/9.8 kg
weight of water =(560/9.8)*74% kg
atomic mass of hydrogen=1g/mol
atomic mass of oxygen=16g/mol, so
atomic mass of water=2x1+16=18g/mol