A boat moves at 17 km/hr downstream and at 9 km/hr upstream in a river. A plastic bottle falls into the same river and floats freely with the current. How far will the current carry the bottle in 3 hours?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 12 km
A freely floating bottle has no speed of its own; it moves at the speed of the stream. The stream’s speed is half the difference of the downstream and upstream speeds.
Speed of the stream \(\displaystyle =\frac{17-9}{2}=4\) km/hr
Distance carried in 3 hours \(=4\times3=12\) km