A kayaker paddles 21 km downstream in 3 hours. The speed of the current is 2 km/hr. What is the kayaker’s speed in still water?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 5 km/hr
The downstream speed is the kayaker’s own speed plus the current, so the current is taken away to get the speed in still water.
Downstream speed \(\displaystyle =\frac{21}{3}=7\) km/hr
Speed in still water \(=7-2=5\) km/hr