Question

The area of a rectangular field is $48m^2$ and one of its sides is 6 m. Then the lady takes ___ sec to cross the field diagonally at the rate of 20 m/minute.

Answer 1

Area of a rectangular field $=48m^2$
One side = 6 m
$\therefore$ Other side $=\frac{48}{6}=8m$

Suppose ABCD is a rectangular field and BD is one of its diagonals.
$BD=\sqrt{(AB{)}^2+(AD{)}^2}$
$=\sqrt{(6m{)}^2+(8m{)}^2}$
$=\sqrt{36m^2+64m^2}=\sqrt{100m^2}$
=10 m
A lady crosss the field diagonally at the rate of 20 m/minute.
Time taken to cover 20 metres = 1 min (60 sec)
Time taken to cover 10 metres $=\frac{1}{2}min\left(30sec\right)$
The lady takes $\frac{1}{2}$ min (30 sec) to cross the field.