Question

A race boat covers a distance of $60km$ downstream in one and a half hour. It covers this distance upstream in $2$ hours. The speed of the race boat in still water is $35km/hr.$ Find the speed of the steam.

Answer 1

Let The Speed Of Stream Be $xkm/hr.$

Now Speed Upstream $=35-x$

Speed Downstream $=35+x$

Now $Time=\frac{Distance}{Speed}$

$\frac{3}{2}=\frac{60}{35+x}$

And

$2=\frac{60}{35-x}$

$\Rightarrow 105+3x=120$

$\Rightarrow 3x=15$

$\Rightarrow x=5km/hr.$

Check By Solving Other Equation

$2=\frac{60}{35-x}$

$\Rightarrow 70-2x=60$

$\Rightarrow 2x=10$

$\Rightarrow x=5km/hr.$

Hence, the speed of the stream is $5km/hr.$