If the interest on ₹ $12000$ is more than the interest on ₹ $10000$ by ₹ $500$ in $3$ $years$,the rate percent per annum is:

$A$ man invests a certain sum of money at $6 \%$ $p.a.$ simple interest and another sum at $7 \%$ $p.a.$ simple interest. His income from interest after $2$ $years$ was $Rs. 354$. One-fourth of the first sum is equal to one-fifth of the second sum. Find the total sum (in $Rs.$) he invested.

What annual payment (in $Rs.$) will discharge a debt of $Rs. 770$ due in $5$ years,the rate of interest being $5 \%$ per annum?

The rate of simple interest (in $\%$) for which a sum of money becomes $5$ times of itself in $8$ years is:

$A$ man invested $\frac{1}{3}$ of his capital at $7 \%$,$\frac{1}{4}$ at $8 \%$,and the remainder at $10 \%$. If the annual income is ₹ $561$,the capital (in ₹) is:

The population of a city increases at the rate of $5 \%$ $p.a.$ If the present population of the city is $370440$,then what was its population (in $lakh$) $3$ years ago?