Find the $4^{th}$ proportional to $4, 16$ and $7$.

Two numbers are in the ratio $1: 2$. If $7$ is added to both,the ratio changes to $3: 5$. The greatest number is:

The price of a diamond is directly proportional to the square of its weight. $A$ man accidentally broke the diamond into three pieces in the ratio of $3:5:7$ and thus lost ₹ $42600$. What was the original price (in ₹) of the diamond?

$A, B, C$ and $D$ share a property worth $₹ 77500$. If $A:B = 3:2$,$B:C = 5:4$ and $C:D = 3:7$,find the share of $B$ (in $₹$).

An amount of ₹ $1200$ is distributed among $A, B$ and $C$ in the ratio of $5: 7: 13$. What is the difference between the shares (in ₹) of $C$ and $B$?

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