For spherical objects, such as these planets, the volume is calculated by the equation,
V = 4πr³ / 3
where V is volume and r is the radius. To determine the number of Plutos that would fit in the Earth, divide the volume of Earth by the volume of Pluto.
V(E) / V(P) = (4π(6371 km)³ / 3) / (4π(1161 km)³ / 3)
= 165.2
Thus, the answer is approximately 165.