Question

A man can row 4km/h in still water and he finds that it takes him twice as long to row up as to row down the river. Find the rate of stream?

Answer 1

Let the speed of stream be x Km/h
Hence, upstream speed of man = 4 - x km/h
Downstream speed of man = 4 + x km/ h
If the distance travelled one way = d km
The time taken upstream $=\frac{d}{(4-x)}hrs$
The time taken downstram $=\frac{d}{(4+x)}hrs$
$\to \frac{d}{(4-x)}=2\frac{d}{4+x}$
8 - 2x = 4 - x
$3x=4\to x=\frac{4}{3}kmph$. or 1.33 kmph