A boat can go 360 m in still water in 2 min. If the speed of the stream is 2 m/sec, how much time will it take to cover the same distance downstream?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 72 sec
Going downstream, the stream carries the boat along, so its speed is the speed in still water plus the speed of the stream.
Speed in still water \(\displaystyle =\frac{360}{2\times60}=3\) m/sec
Downstream speed \(=3+2=5\) m/sec
Time downstream \(\displaystyle =\frac{360}{5}=72\) sec