1. The problem statement, all variables and given/known data The mean radius for the orbit of the planet Mars about the sun is 2.28 * 1011m. If the radius of the orbit of the earth around the sun is 1.49 * 1011m. If it takes the earth 1 year (365 days) to orbit the sun, how long (in earth days) is the year on mars? So this is the question is giving me trouble and was wondering if someone could help me out. 2. Relevant equations 4pi2 * Ro / To2 = Gme/ Ro2 I think this equation might be use full but i am not sure. 3. The attempt at a solution I think i have the period of the earth because 365 days = 31 556 926s correct? Sorry i am not sure how much information i have to work with here and i am just stuck.