Solution:
The ratio of weights of an object in the coal mine, at sea level and at the top of the mountain are .Weight of an object is a product of its mass and acceleration due to gravity. For every object mass is constant and the value of changes according to its height or depth.
The variation of g at depth is
is the acceleration due to gravity at the surface of earth =
= radius of earth
The variation of g is at height is
For a coal mine at depth and at sea level, and at a height for a mountain, the ratio of weights is
Hence the ratio is,