The distance of Neptune and Saturn from sun are nearly 1013 and 1012 meters respectively. Assuming that they move in circular orbits, their periodic times will be in the ratio :

√10   100   10√10   1 /√10

10√10

Kepler’s third law T2 ∝ R3 : \(\Rightarrow \frac{T_{Neptune}}{T_{Saturn}} = [\frac{R_{Neptune}}{R_{Saturn}}]^{3/2}\)   = \([\frac{10^{13}}{10^{12}}]^{3/2}\)   = \(10\sqrt{10}\)