Question

A circular pond is to be surrounded by a gravel path to find the square feet of gravel needed if we know the pond has a radius of 200 ft and the radius of the whole space is 250 ft

Answer 1

So we can just subtract the area of the pond from the area of the whole space.
So to find the area of the pond, 
200²$\pi$.
That would equal about 125663.7 ish.
And then the whole area would be
250²$\pi$.
That would equal about 196349.541
And then just do
196349.541 - 125663.7 = 70685.741 ish
So they would need about 70685.741 square feet of gravel.