Yes, you are flummoxed. G is not g. G is the universal gravitation constant, and g is Earth gravitation constant, but neither is constant. G varies in the third decimal, and g depends on where you are and what is near you.
I used the upper case G as it was the beginning of a sentence. Note the (g). I'll let you in on the trick of the question. The force of gravity is not measured from the surface, but from the centre of the earth. Thus, the gravitational force at 1000km above the surface is 75% of that from the surface. The differences of the force between the Marianas Trench and Mount Everest is minute, but measurable. That should clarify everything. Check your nearest physics book.
This post was edited by Element 99 at June 29, 2018 5:16 PM MDT