The compound interest on ₹ $30000$ at $7 \%$ per annum is ₹ $4347$. The period (in years) is

$A$ sum of money at compound interest amounts in two years to Rs. $2809,$ and in three years to Rs. $2977.54.$ Find the rate of interest and the original sum.

Rohit invested some amount at the rate of $6\%$ per annum and at the end of $3$ years he received ₹ $8730$ as simple interest. How much compound interest (in ₹) will he receive on the same amount and same rate of interest after $2$ years?

$A$ man borrows ₹ $3825$ to be paid back with compound interest at the rate of $4 \%$ per annum by the end of $2$ years in two equal yearly instalments. How much will be each instalment (in ₹)?

$A$ man gets a simple interest of $Rs. 1000$ on a certain principal at the rate of $5$ $p.c.p.a.$ in $4$ years. What compound interest (in $Rs.$) will the man get on twice the principal in two years at the same rate?

The difference between simple and compound interest on a sum of $10000$ is $64$ for $2$ years. Find the rate of interest. (in $\%$)