Question

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?

Answer 1

kepplers third law: the square of the orbital period is proportional to the cube of mean radius.

4^2/T^2=5^3/12^3

solve for period T