Question

John cycling at a constant speed of 10 km/hour reaches his school in time. If he cycles at a constant speed of 15Km/hour ...he reaches his school in 12 minutes early. How many kilometre he has to cycle for his school??​

Answer 1

Answer:

John cycling at a constant speed of 10 km/hour reaches his school in time.

$s = \frac{d}{t} \\ 10 = \frac{d}{t}$

If he cycles at a constant speed of 15Km/hour, he reaches his school in 12 minutes early.

$15 = \frac{d}{t - \frac{12}{60} }$

Divide the equation -

$\\ \frac{10}{15} = \frac{t - 0.2}{t} \\ \frac{2}{3} = \frac{t - 0.2}{t} \\ 2t = 3t - 0.6 \\ t = 0.6 \: hr \\ t = 36 \: minutes$

So,

he has to cycle for his school,

$d = s \times t \\ d = 10 \times 0.6 = 6 \: km$