A boy travels 5 km towards the South and then turns left and travels 5 km. After that, he turns to his right and walks 7 km. How far is he from the starting point finally?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 13 km
Each turn is taken from the direction the boy is facing at that moment:
He walks 5 km South
Facing South, a left turn is East: he walks 5 km
Facing East, a right turn is South: he walks 7 km
Where he ends:
North-South: 5 km and then 7 km South, so he ends 12 km South of the start
East-West: he ends 5 km East of the start
The distance from the start (the two distances are at right angles, so by Pythagoras):
Distance \(=\sqrt{12^2+5^2}=\sqrt{169}=13\) km