A ship sailed 3 km due south, 7 km due east, 9 km due north and 5km due west. How far is the ship from the starting point?

(B) 6.3 km

Explanation

3km S and 9km N leaves 6km N. 7km E and 5km W leaves 2km E. Visualize right triangle with legs 6 * 2. Correct displacement must be between 6km and 8km.