Question

A horse can be tied at the centre of a square field with a rope of $140$ metre length. If a boy runs around this field at $10$ metre per second, in what time can the boy complete four rounds of this field?

Answer 1

Side of the field $=2\times 140$ metre
$\therefore$ Perimeter $=4\times (2\times 140)=1120$ metre
Total distance $=4\times perimeter=4\times 1120=4480metre$
$Time=\frac{Distance}{Speed}=\frac{4480}{10}=448second$
$=7$ minute, $28$ seconds.