The population of a country is $10$ crore and it is the possibility that the population will become $13.31$ crore in $3$ years. What will be the annual rate per cent of this growth?

A sum put out at $4 \%$ compound interest payable half-yearly amounts to ₹ $6632.55$ in $1 \frac{1}{2}$ years. The sum (In ₹) is

The simple interest on a certain sum at $4 \%$ per annum for $2$ years is ₹ $80$. The compound interest (In ₹) on the same sum for the same period is

What is $C.I.$ (In $Rs.$) on $Rs. 7500$ for $4$ years if the rate of interest is $10 \%$ p.a. for the first $2$ year and $20 \%$ $p.a.$ for the next $2$ year?

The difference between compound and simple interest at a certain rate on $Rs. 2000$ at the end of two years is Rs. $12.8 .$ The rate of interest (In $\%$) per annum is