A boat can travel at a speed of 15.5 km/h in still water. If the speed of the stream is 4.5 km/h, then how much time will it take to go 76 km downstream and 104.5 km upstream?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 13 hours 18 minutes.
Given:
The boat can travel at a speed of 15.5 km/h in still water and the speed of the stream is 4.5 km/h,
So,
The downward speed of the boat = 15.5 + 4.5 = 20 km/h
The upward speed of the boat = 15.5 - 4.5 = 11 km/h
According to the question:
The time will take to go 76 km downstream and 104.5 km upstream = 76/20 + 104.5/11
⇒ 3.8 + 9.5
⇒ 13.3 hours = 13 hours 18 minutes