Using Keplers Law, T is proportional to r^ (3/2) T^2 is proportional to r^3 [Tj / Te]^2 = [rj / re]^3 => Tj^2 = [rj / re]^3 x Te^2 => Tj^2 = [5.2 / 1.0]^3 x (1.0)^2 => Tj^2 = 140.6 => Tj = squareroot of 140.608 => Tj = 11.85 year, which is approximately 12 years So the Jupiters orbital period in Earth years is 12 years.