Aman can go downstream thrice as fast as he can go upstream between two specific points on a river. If the river flows at 8 kmph, what is the speed of the boat in still water (in kmph)?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 16 kmph
Going downstream, the river’s speed is added to the boat’s speed in still water; going upstream it is subtracted. Let the speed in still water be \(b\) km/h.
Downstream speed \(=b+8\); upstream speed \(=b-8\)
Downstream is thrice as fast: \(b+8=3(b-8)\)
\(b+8=3b-24\)
\(2b=32\), so \(b=16\) km/h