In a mixture of $60 \, \text{litres}$,the ratio of milk and water is $2:1$. What amount of water (in $\text{litres}$) must be added to make the ratio of milk and water $1:2$?

The mean proportional of $0.25$ and $0.04$ is

$A$ and $B$ are two alloys of gold and copper prepared by mixing metals in the ratio $7:2$ and $7:11$ respectively. If equal quantities of the alloys are melted to form a third alloy $C$,the ratio of gold and copper in $C$ will be

The difference between a two-digit number and the number obtained by interchanging the digits is $36$. What is the difference between the sum and the difference of the digits of the number if the ratio between the digits of the number is $1:2$?

If $A: B = \frac{1}{2}: \frac{3}{8}$,$B: C = \frac{1}{3}: \frac{5}{9}$ and $C: D = \frac{5}{6}: \frac{3}{4}$,then the ratio $A: B: C: D$ is

If $\left(x+\frac{1}{x}\right):\left(x-\frac{1}{x}\right)=5:5$,then the value$(s)$ of $x$ is/are: