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 km west and 4 km south. Which further route could bring him back to his starting point, if the same route is not repeated?
Answer & explanation
Answer: (b) 3 km east, then 1 km north
After 3 km north, 3 km west and 4 km south he is 3 km west and 1 km south of the start. Driving 3 km east and then 1 km north brings him back without retracing any stretch.
- Take the start as (0, 0), with east and north positive.
- 3 km north → (0, 3); 3 km west → (−3, 3); 4 km south → (−3, −1).
- To return he must go 3 km east and 1 km north.
- (b): 3 km east → (0, −1), then 1 km north → (0, 0). Neither stretch repeats an earlier one.
- Check: (a) ends at (0, −3), (c) at (−5, 0), (d) at (−3, −3).
Remember · Track direction problems as coordinates: add north and east, subtract south and west, then read off the move back to (0, 0).
Question and answer: UPSC's official GS Paper II (2016, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·