Question

A students walks from his house at less 4 km per hour and reaches his school late by 5 minutes. If his speed has been increase by 5 km per hour then he would have reached 10 minutes early. The distance of the school from his house is

• A. $\frac{3}{5}km$
• B. $5$km
• C. $6$km
• D. $4$km

Answer 1

Answer: (B)

$5$km

Let the actual time be 't'
and distance be x
Now according to first condition, we have
$\frac{x}{4}=t+\frac{5}{60}$
And according to Second condition, we have
$\frac{x}{5}=t-\frac{10}{60}$
$60x=4t+20$
$60x=5t-50$
Subtracting equation 1 from 2, we have
$0=t-70$
$\therefore t=70$
Putting the value of t we get $x=5km$