A boatman rows 96 km downstream in 8 hours. The speed of the stream is 4 km/hr. How much time will he take to row 8 km upstream?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 2 hours
Downstream speed = boat speed + stream speed and upstream speed = boat speed − stream speed. The downstream trip gives the boat speed.
Downstream speed \(\displaystyle =\frac{96}{8}=12\) km/hr
Speed of the boat in still water \(=12-4=8\) km/hr
Upstream speed \(=8-4=4\) km/hr
Time for 8 km upstream \(\displaystyle =\frac{8}{4}=2\) hr