It can be shown that for a uniform sphere the force of gravity at a point inside the sphere depends only on the mass closer to the center than that point. The net force of gravity due to points outside the radius of the point cancels.

Question

It can be shown that for a uniform sphere the force of gravity at a point inside the sphere depends only on the mass closer to the center than that point. The net force of gravity due to points outside the radius of the point cancels.
	
Part A
How far would you have to drill into the Earth, to reach a point where your weight is reduced by 8.0\% ? Approximate the Earth as a uniform sphere.

g= GMe/re^2
g'=.92GMe/re^2 =GMe(r/re)^3

then it reduces to

.92re=r^3, and that leads to
r=re *cubrt(.92)

the r is, 6205.11, and shouldn' t I need to subratc it from radius of earth which is 6380-6205.11, it is equal to "174.89" but my answer fails. Please help, ty for ur care now.