Question

In one fortnight of a given month, there was a rainfall of $10$ cm in a river valley. If the area of the valley is $7280$ km${}^2$, show that the total rainfall was approximately equivalent to the addition to the normal water of three rivers each $1072$ km long, $7$5 m wide and $3$ m deep.

Answer 1

Given:
Area of the valley $=7280$ km${}^2$
Volume of rainfall in the area = $7280\times 10\times 0.00001=0.728{km}^3$ (Converting $1$ cm to km)
Volume of water in $3$ rivers $=3\times 1\times b\times h$ ($3\times Volume=3\times l\times b\times h$)

$=3\times 1072\times 75\times 0.001\times 3\times 0.001$ (Converted $1$m to km)

$=0.723$ km${}^3$
So, the $2$ valleys are nearly similar.