Given :
Our weight is 600 Newton on the earth.
To Find :
How far should you go from the center of the earth so that it will be 300 Newton.
Solution :
Acceleration due to gravity at depth d is given by :
At earth surface, mg = 600 N ...1)
At depth d, mg' = 300 N ...2)
Dividing 1) and 2), we get :
Therefore, we should go in the depth of distance half the radius of earth.