$A$ mixture of $48$ litre of milk and water contains $10 \%$ of water. How much water must be added to make $20 \%$ water in the new mixture?

The ratio in which two sugar solutions of the concentrations $15 \%$ and $40 \%$ are to be mixed to get a solution of concentration $30 \%$ is

Gold is $19$ times as heavy as water and copper is $9$ times. In what ratio should these metals be mixed so that the mixture may be $15$ times as heavy as water?

Haresh earned ₹ $4000$ per month. From the last month,his income increased by $8\%$. Due to a rise in prices,his expenditure also increased by $12\%$ and his savings decreased by $4\%$. Find his increased expenditure and initial savings.

The ratio of milk and water in mixtures of four containers are $5:3$,$2:1$,$3:2$,and $7:4$,respectively. In which container is the quantity of milk,relative to water,the minimum?

In what ratio must a grocer mix two varieties of tea worth $Rs. 60$ per $kg$ and $Rs. 65$ per $kg$ so that by selling the mixture at $Rs. 68.20$ per $kg$ he may gain $10\%$?