Discussion Forum

A man can row 18 kmph in still water. It takes him thrice as long to row up as to row down the river. Find the rate of stream.

Answer:

Explanation:

Let man's rate upstream be $x$ kmph.

Then, his rate downstream $=3x$ kmph.

$\therefore$ Rate in still water $=\frac{1}{2}(3x+x)$ kmph $= 2x$ kmph.

So, $2x=18$ or $x=9$.

$\therefore$ Rate upstream $= 9$ km/hr, Rate downstream $=27$ km/hr.

Hence, rate of stream $= \frac{1}{2}(27-9)$ km/hr = 9 km/hr.