Well...if the water level rose by 200 ml, each of the 4 golf b***s must have contributed to a 50ml rise.......thus, the volume of a single ball must be 50 ml.
Well...if the water level rose by 200 ml, each of the 4 golf b***s must have contributed to a 50ml rise.......thus, the volume of a single ball must be 50 ml.