Question

A boat goes downstream and covers the distance between two ports in $4$ hours. It covers the same distance in $6$ hours when it goes upsream. If speed of the boat is $5km/h$. then find the speed of water.

Answer 1

Let speed of boat be $xkm/hr$ speed of water be $ykm/he$

$\therefore$ Let total distance be $d$

$\therefore \frac{d}{x+y}=4$.......... $\left(1\right)$

$\therefore \frac{d}{x-y}=5$ ........... $\left(2\right)$

$\therefore \frac{x-y}{x+y}=\frac{4}{5}$

$\therefore 5x-5y=4x+4y$

$\therefore x=9y$

Now $x=5km/hr$

$\therefore y=\frac{x}{9}=\frac{5}{9}km/hr$

Speed of water is $\frac{5}{9}km/hr$