In a mixture of $75 \, litres$,the ratio of milk to water is $2:1$. The amount of water to be further added to the mixture so as to make the ratio of milk to water $1:2$ will be (in $litres$):

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

In a laboratory,two bottles contain a mixture of acid and water in the ratio $2:5$ in the first bottle and $7:3$ in the second. The ratio in which the contents of these two bottles should be mixed such that the new mixture has acid and water in the ratio $2:3$ is

$A$ shopkeeper bought $15 \text{ kg}$ of rice at the rate of $Rs. 29$ per $\text{kg}$ and $25 \text{ kg}$ of rice at the rate of $Rs. 20$ per $\text{kg}$. He sold the mixture of both types of rice at the rate of $Rs. 27$ per $\text{kg}$. His profit in this transaction is (in $Rs.$)

$A$ and $B$ are two alloys of gold and copper prepared by mixing metals in the ratio $5:3$ and $5:11,$ respectively. Equal quantities of these alloys are melted to form a third alloy $C.$ The ratio of gold and copper in the alloy $C$ is

In what ratio must sugar at $Rs. 2$ per $kg$ be mixed with sugar at $Rs. 3.50$ per $kg$ so that the mixture is worth $Rs. 2.50$ per $kg$?