Monu rides his bicycle northwards, then turned left and rides one km and again turned left and rides 2 km. Monu found himself exactly one km west of his starting point. How far did he ride northwards initially?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 2 km
Each turn is taken from the direction Monu is facing at that moment:
Facing North, a left turn is West: he rides 1 km West
Facing West, a left turn is South: he rides 2 km South
He ends 1 km West of the start, which is the 1 km he rode West, so he is neither north nor south of the start. The 2 km he rode South must therefore cancel his first ride North, which was 2 km.