Question

The speed of a boat in still water is $10$ km/hr. If it can travel $26$ km downstream and $14$ km upstream in the same time, then the speed of the stream is

• A. $2$ km/hr
• B. $2.5$ km/hr
• C. $3$ km/hr
• D. $4$ km/hr

Answer 1

The correct option is C $3$ km/hr

Let the speed of the stream be $x$ km/hr.
Then, speed of downstream $=(10+x)$ km/hr.
and speed of upstream $=(10-x)$ km/hr.

According to question,
$\frac{26}{10+x}=\frac{14}{10-x}$
$\Rightarrow 260-26x=140+14x$
$\Rightarrow 40x=120$
$\therefore x=3$ km/hr