posted by Jeremiah .
The radius of planet X is 5.0 bleems. It takes 4 earth years to complete it's orbit. Another planet, Z, orbits the same sun and has an orbit with the radius of 12 bleems.
How long does it take for planet Z to complete an orbit?
kepplers third law: the square of the orbital period is proportional to the cube of mean radius.
solve for period T