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?

The production of a factory grows at a $8 \%$ $p.a.$ What will be its production (In $lakh tonnes$) for the year $2010$ , if its production in $2008$ was $70$ lakh tonnes?

Albert invested an amount of ₹ $8000$ in a fixed deposit scheme for $2$ years at compound interest rate of $5 \%$ per annum. How much amount (In ₹) will Albert get on maturity of the fixed deposit?

Mr. Dua invested money in two schemes $A$ and $B$ offering compound interest at $8 \%$ per annum and $9 \%$ per annum respectively. If the total amount of ineterest accrued through two schemes together in two years was ₹ $4818.30$ and the total amount invested was ₹ $27000$ . What was the amount (In ₹) invested in scheme $A$.

What is the rate of interest (in $\%$) if simple interest earned on a certain sum for the 3 rd year is $₹ 2,000$ and compound interest earned in 2 years is ₹ $4,160 ?$

If a sum of money at compound interest amounts to thrice itself in $3$ years, then in how many years will it be $9$ times itself?