Question

Water in a canal, $30dm$ wide and $12dm$ deep, is flowing with a velocity of $20km/h$. How much area will it irrigate in $30$ min, if $9cm$ of standing water is desired?

• A. $122$
• B. $144$
• C. $220$
• D. None of the above

Answer 1

The correct option is D None of the above

Given, width of the canal $=30dm=3m$ ...$(1m=10dm)$

Depth of canal $=12dm=1.2m$

Velocity of flowing water $=20km/h=20,000m/h$

Therefore, length of water column is formed in 30 minutes $=20000\times \frac{1}{2}=10,000m$

Let $a$ $m^2$' of area is to be irrigated and it also mentioned that $9cm$ of standing water is required.

According to the given condition,

$a\times \frac{9}{100}=10,000\times 1.2\times 3\Rightarrow a=4,00,000m^2$

Hence, $4,00,000m^2$ of area is irrigated.