Question

From a container, 6 litres milk was drawn out and was replaced by water. Again 6 litres of mixture was drawn out and was replaced by the water. Thus the quantity of milk and water in the container after these two operations is 9 : 16. The quantity of mixture is

• A. 15
• B. 16
• C. 25
• D. 31

Answer 1

The correct option is A 15

let $k$ be the quantity of mixture

$\frac{milkleft}{wateradded}=\frac{9}{16}$

It means $\frac{milkleft}{initialmilkqty}=\frac{9}{9+16}=\frac{9}{25}$

$\frac{9}{25}={(1-\frac{6}{k})}^2$

$\frac{3}{5}=(1-\frac{6}{k})$

$k=15liter$