Question

The area of rectangular field is $3584m^2$ and its length is $64m$. A boy runs around the field at rate of $6km/hr$. How long will he take to go $5$ around it?

Answer 1

Given area of field = $3584m^2$

length = 64 m

We know area - length $\times$ breadth = $l\times b$

$b=\frac{3584}{64}=56m$

Now Perimeter of field = 2[l+b]

=2[64+56]

Perimeters of field = 2[120]= 240 m.

for 5 rounds perimeter = $240\times 5=1200m$

Given speed of boy = 6 km/h = $6\times \frac{5}{18}=\frac{5}{3}m/sec$

then time taken to cover 1200 m distance = $\frac{1200}{5}\times 3$

Time = $240\times 3sec$

or Time = $\frac{240\times 3}{60}min=12min$

$\therefore$ 12 min required to complete 5 rounds of field.