Question

How long will a girl take to walk around the boundary of a square field of area $9$ hectars at the rate of $6$ kilometers per hour?

Answer 1

Solution :

We know that

$1$ hectare $=10000m^2$

$9$ hectare $=90000m^2$

Therefore Area of square $=90,000$

Side${}^2=90,000$

Side$=\sqrt{90000m^2}$

Side $=300m$

Therefore Length of perimeter $=4\times$ side

$=4\times 300$

$=1200m$

Now convert into km

$=\frac{1200}{1000}km=1.20km$

Therefore, time $=\frac{\text{distance}}{\text{speed}}$

$=\frac{1.2km}{6kmperhr}$

$=\frac{1}{5}$ hour

$=\frac{1}{5}\times 60$ minues

$=12$ minutes