Question

How long will it take for a boy to run around a square field of area $25$ hectare at $10$ km per hour?

Answer 1

side of the square $=\sqrt{Area}$
$=\sqrt{25\times 10000}m$
$=500m$
$\therefore$ Distance to run $=$ Perimeter of the filed
$=4\times 500m=2km$
Time taken by a boy $=\frac{Distance}{Speed}$
$=\frac{1}{10}hr=12min$