According to Kepler's third law, T2 ∝ R3
where TS and TE are the period of revolution of Saturn and the earth and RS and RE are the distances of Saturn and the earth from the sun respectively.
Given RE = 1.50 × 1011m
TS = 30 × TE
∴ RS = 1.50 × 1011 × \((\frac {30T_E}{T_E})^{2/3}\)
= 1.50 × 1011 x 302/3
= 1.448 × 1012 m
= 1.448 × 109 km.