Question

The time required to cover a given distance is inversely proportional to the average speed of a vehicle. If the speed is $40km/hr$, it takes $3$ hours to cover a certain distance. Find the average speed of the vehicle, if the same distance is to be covered in $2$ hours

Answer 1

$Time\left(t\right)\propto \frac{1}{Speed\left(s\right)}$
$t=\frac{k}{s}$
$\therefore ts=k$
$\therefore k=40\times 3=120$
Now, $t=2hours$
$\therefore 120=2\times s$
$\therefore s=60$
The required speed is $60km/hr$.