$A$ sum of money at simple interest becomes four times in $24$ years. The rate per cent of interest per annum is

$A$ certain sum of money amounts to ₹ $918$ in $2$ $years$ and ₹ $969$ in $3.5$ $years$ at simple interest. What is the rate of interest (in $\%$ $p.a.$)?

The effective annual rate of interest (in $\%$) corresponding to a nominal rate of $13 \%$ per annum payable half-yearly is:

If the amount obtained by Mahesh by investing ₹ $1500$ for $2 \frac{1}{2}$ years at the rate of $8 \%$ $p.a.$ is equal to the amount obtained by Suresh by investing a certain sum for $2$ years at $5 \%$ $p.a.$ simple interest,then the sum invested by Suresh is

$A$ sum of money will double itself in $16$ years at simple interest at an yearly rate of (in $\%$):

$A$ sum of ₹ $8000$ is divided into two parts. The simple interest on the first part at the rate of $21 \%$ per annum is equal to the simple interest on the second part at the rate of $35 \%$ per annum. What is the interest (in ₹) of each part?