Question

A tank can hold 750 L of water. At present, it is only 20% full. How many litres of water should be poured into the tank, so that it becomes 60% full?

• A. 100 L
• B. 200 L
• C. 300 L
• D. 400 L

Answer 1

The correct option is C 300 L

Capacity of the tank = 750 L
Suppose, 20% of 750 L = $x$ L
Therefore, 60% of 750 L = $y$ L

So, $\frac{x}{750}=\frac{20}{100}\text{and}\frac{y}{750}=\frac{60}{100}$
$\Rightarrow x=\frac{750\times 20}{100}=150\text{L}$
$\text{and}y=\frac{750\times 60}{100}=450\text{L}$

To raise the water level from 20% to 60%, we need to add (y-x) L of water,
i.e., 450 - 150 = 300 L