After watching a space documentary, Lou speculates that there is money to be made by combining the phenomenon of weightlessness in space with the widespread longing for weight loss in the general population. Researching the matter, he learns that the gravitational force on a mass m at a height h above the earth's surface is given by F = mgR_E²/(R_E + h)², where R_E is the radius of the earth (about 6370 km) and g is the acceleration due to gravity at the earth's surface. 

(a) Using this expression, find the weight in newtons and pounds of an 83-kg person at the earth's surface. 

(b) If this person were weight-conscious and rich, and Lou managed to sell the person a trip to a height of 400 km above the earth's surface, how much weight would the person lose? 

(c) What is the person's mass at this altitude?