State any assumption(s) you make
Well, I decided to draw a circle with a center at the origin of a Cartesian plane. It had radius r so it's coordinates on the axes were (0, r), etc.
I then drew another circle inside with half the radius so (0, 1/2r), etc.
So every point needs to be inside the center but not on it and I wasn't given particular values. How should I go about doing this further?
Hint: What about take the ratio $$\frac{\text{Area of the small circle}}{\text{Area of the big circle}}=\frac{\pi\left(\frac{1}{2}r^2\right)}{\pi r^2}=\frac{1}{4}?$$