Question

A boy covers a distance of $25km$ in $4$ hours partly on foot at the rate of $3.5kmph$ and partly on cycle at $9kmph$. Find the distance covered on foot.

• A. $7km$
• B. $6.75km$
• C. $5.42km$
• D. None of these

Answer 1

The correct option is A $7km$

Let distance covered by foot is 'x' & in time '$t_1$'

the $x=3.5t_1$ $[\because speed=\frac{Distance}{time}]$

$(25-x)=9t_2$

As $t_1+t_2=4\Rightarrow \frac{x}{3.5}+\frac{(25-x)}{9}=4$

$\Rightarrow 9x-3.5x=38.5$

$\Rightarrow x=7km$