According to the Kepler's law, you have this proportion= , where T is the period, D is the mean distance, the index "e" relates to the Earth, while the index "v" relates to Venus. You can use ANY consistent units for the distance; I will use millions of kilometers to avoid unnecessary degrees of 10. So, my proportion is = , which implies = = 0.38, = = 0.62. Answer. The period for Venus is 0.62 of an year, or 225 days. Check. The Internet sources say 224.7 days.