A satellite is placed in a noncircular orbit about the Earth. The farthest point of its orbit

Question:

A satellite is placed in a noncircular orbit about the Earth. The farthest point of its orbit (apogee) is 4 Earth radii from the center of the Earth, while its nearest point ( perigee ) is 2 Earth radii from the Earth's center. If we define the gravitational potential energy U to be zero for an infinite separation of Earth and satellite, find the ratio Uperigee / Uapogee?