Question

Starting from his house one day,a student walks at a speed of 2.5 kmph and reaches his house 6 minutes late.Next day he increases his speed by 1kmph and reaches school 6 minutes early.How far is the school from his house.

Answer 1

Let the distance be $x$ km

Difference in timing $=12$ min $=\frac{12}{60}$ hr $=\frac{1}{5}$ hr

$\therefore$ $\frac{2x}{5}-\frac{2x}{7}=\frac{1}{5}$

$\Rightarrow 14x-10x=7$

$x=1\frac{3}{4}$ km.