A 77.5 kg man, who is engaged in light activity and who is not sweating, uses internal energy at a rate of 247.5 kcal/h. The man then begins strenuous exercise, requiring 793.6 kcal/h. Assuming that the extra heat generated is dissipated through sweating and that 25% of the sweat evaporates, find the man's rate of sweat production in L/h. (Use 580 kcal/kg for the heat of vaporization of water at body temperature.)