A boat goes 36 km upstream in 4 hours. The speed of the stream is 2 km/hr. What is the speed of the boat in still water?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 11 km/hr
The upstream speed is the boat’s speed less the stream’s speed, so the stream’s speed is added back to get the speed in still water.
Upstream speed \(\displaystyle =\frac{36}{4}=9\) km/hr
Boat \(-\,2=9\), so speed of the boat in still water \(=9+2=11\) km/hr