Question

In a $729$ liters mixture if milk and water , the ratio of milk to water is $7:2$ to get a new mixture containing milk and water in the ratio of $7:3$, the amount of water to be added is :

• A. $81$
• B. $71$
• C. $56$
• D. $50$

Answer 1

The correct option is A $81$

Total mixture=729 liters

Amount of milk in mixture $=\frac{7}{9}\times 729=567liters$

Amount of water in mixture $=\frac{2}{9}\times 729=162liters$

Let $x$ liter is water is added to get the ratio $7:3$ then

$\Rightarrow \frac{567}{162+x}=\frac{7}{3}$

$\Rightarrow 1701=1134+7x$

$\Rightarrow 7x=567$ $\Rightarrow x=81liters$

Hence $81$ liters water is added.