A person X was driving in a place where all roads ran either north-south or east-west, forming a grid. Roads are at a distance of 1 km from each other in a parallel. He started at the intersection of two roads, drove 3 km north, 3 west and 4 km south. Which further route could bring him back to his starting point, if the same route is not repeated?
- A.3 km east, then 2 km south
- B.3 km east, then 1 km north
- C.1 km north, then 2 km west
- D.3 km south, then 1 km north
▶ Answer & Explanation
Correct answer: D. 3 km south, then 1 km north
The person starts at an origin (0,0). Driving 3 km north moves the position to (0,3). Then driving 3 km west moves the position to (-3,3). Finally, driving 4 km south moves the position to (-3,-1). To return to the origin (0,0), the person needs to move 3 km east and 1 km north. Therefore, a route of 3 km east followed by 1 km north will bring the person back to the starting point.
Source: UPSC csat 2016