Person A is on the level plain and is attempting to signal down the airplane at 5,500 ft. by creating large letters like S.O.S. Though, pilot (Pilot B) of this paticular plane doesn't have 20-20 vision. In fact pilots' vision is only 7/8 as good as someone with perfect 20-20 vision. To get Pilot Bs' attention so that he may read out message created by Person A clearly, how much bigger each letter have in comparison to Person A if Person A is 6' 0" ?