Question

The speed of a boat in still water is $10$ km/hour if it can travel $26$ km downstream and $14$ Km upstream at the same time, the speed of the stream is

• A. $4$ km/hour
• B. $4.5$ km/hour
• C. $5$ km/hour
• D. $3$ km/hour

Answer 1

Answer: (D)

$3$ km/hour

Let the speed of the stream be $x$ km/hour.

Then speed of the boat in downstream will be $(10+x)$km/hour.

And speed of the boat in upstream will be $(10-x)$km/hour.

As given,the boat travels 26km downstream and 14km upstream at the same time.

$\frac{26}{10+x}$=$\frac{14}{10-x}$

=$26(10-x)$=$14(10+x)$

=$260-26x=140+14x$

=$120=40x$

$x=3$km/hour

Speed of the stream is 3 km/hour.