Question

Water and Acid are mixed in the ratio 3 : 4 to make a liquid. On mixing 20 more litres of water , the ratio changed to 7 : 4.

Find the original quantity of water content in the mixture.

• A. 15 litres
• B. 18 litres
• C. 12 litres
• D. 21 litres

Answer 1

The correct option is A

15 litres

Let Water = 3x and Acid = 4x

After adding 20 litres we get:
3x + 20 : 4x = 7 : 4

$\Rightarrow \frac{3x+20}{4x}=\frac{7}{4}$

$\Rightarrow 4(3x+20)=7\left(4x\right)$

$\Rightarrow 12x+80=28x$

$\Rightarrow 28x-12x=80$

$\Rightarrow 16x=80$

$\Rightarrow x=5$

$\therefore$ Original Quantity of Water $=3x=3\times 5=15$ litres