The weight of an object in the coal mine, sea level and at the top of the mountain are respectively W1, W2 and W3, then
g at certain depth is g1 = g(1 -d/R)
Weight in mine is w1 = mg1 = mg(1-d/R)
weight at sea level w2 = mg ( acceleration due to gravity is the gravity at sea level)
g at certain height is g11 = GM/(R+h)2
g11 = gR2/(R+h)2
g11 = g(1-2h/R)
weight at mountain is w3 = mg11 = mg(1-2h/R)
w1 < w2 > w3