Ravi starts from his house and moves towards south. He walks 100 m, then turns left and walks 200 m, turns right and walks 500 m. How far is he from his house?
1) `400sqrt5`m
2) 800 m
3) `200sqrt10`m
4) `200sqrt2`m
5) None of these

Explanation

3, `200sqrt(10)m`