A bank employee drives 10 km towards South from her house and turns to her left and drives another 20 km. She again turns left and drives 40 km, then she turns to her right and drives for another 5 km. She again turns to her right and drives another 30 km to reach her bank where she works. What is the shortest distance between her bank and her house?
Answer & explanation
Answer: (b) 25 km
Tracking the turns, the north–south legs cancel out (10 south, 40 north, 30 south) and the east legs add to 20 + 5 = 25 km. The bank is 25 km due East of the house.
- Place the house at (0, 0), East as +x and North as +y.
- 10 km South → (0, −10). Facing South, a left turn faces East: 20 km → (20, −10).
- Left again faces North: 40 km → (20, 30). Right faces East: 5 km → (25, 30).
- Right again faces South: 30 km → (25, 0), the bank.
- The bank is 25 km due East of the house, so the shortest distance is 25 km.
Remember · Add the net East–West and North–South movements separately; use Pythagoras only if both are non-zero.
Question and answer: UPSC's official GS Paper II (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·