Question

A river is running at $2$ km/hr. It took a man twice as long to row up as to row down the river. The rate ( in km/hr) of the man in still water is

• A. $8$
• B. $10$
• C. $4$
• D. $6$

Answer 1

The correct option is D $6$

Let the distance travelled be $D$ km and speed of the man in still water be $x$ km/hr.

Then, speed downstream $=(x+2)$ km/hr
and speed upstream $=(x-2)$ km/hr
Given, $\frac{D}{x-2}=2\times \frac{D}{x+2}$
$\Rightarrow x+2=2x-4$

$\Rightarrow x=6$ km/hr