ANSWERS: 1

The acceleration of gravity is given by GM/r^2 where G is the gravitational constant M is the mass of the object (Mars) and r is the distance from the center of the planet. Suppose R is the radius of Mars. You started with an acceleration GM/R^2 You ended with an acceleration GM/(3R+R)^2 because if it's 3 R from the surface, it's 3R+R from the center. GM/(3R+R)^2 = GM/(16 R^2) which is 1/16 of the starting acceleration.
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