If the simple interest on a certain sum of money for $2$ $years$ is one-fifth of the sum,then the rate of interest (in $\%$) per annum is

Girish invested some money in a bank. After $8$ years,his amount became triple. How many times of the original sum will the money become in $20$ years at simple interest?

What is the interest (in $Rs.$) received on a principal of $Rs. 450$ for $2$ years, if the interest received on $Re. 1$ after $4$ years at the same rate of simple interest is $Rs. 0.40$?

The simple interest on a sum of money is $\frac{8}{25}$ of the sum. If the number of years is numerically half the rate percent per annum,then the rate percent per annum is

$A$ sum of money put at simple interest trebles itself in $15$ years. The rate per cent per annum is (in $\%$):

$A$ person has left an amount of ₹ $1,20,000$ to be divided between his two sons aged $14$ years and $12$ years such that they get equal amounts when each attains $18$ years of age. If the amount gets a simple interest of $5 \%$ per annum,the younger son's share at present (in ₹) is