The difference between simple and compound interest on sum of $10000$ is $64$ for $2$ years. Find the rate of interest.

The difference between the compound interest and the simple interest accrued on an amount of ₹ $18000$ in $2$ years was ₹ $405 .$ What was the rate of interest per cent per annum?

The simple and compound interests on a sum of money for $2$ years are ₹ $8400$ and ₹ $8652$ respectively. The rate of interest per annum is (In $\%$)

If the compound interest on a sum for $2$ years at $12 \frac{1}{2} \%$ per annum is ₹ $510,$ the simple interest (In ₹) on the same sum at the same rate for the same period of time is.

What will be the compound interest on a sum (In ₹) of ₹ $25000$ after $3$ years at the rate of $12 \%$ per annum?

Raghu invested a certain sum in Scheme $X$ for $4$ years.Scheme $X$ offers simple interest at $12$ per cent pa for the firsttwo years and compound interest (compounded annually) at $20$ per cent pa for the next two years. The total interest earned by him after $4$ years is ₹ $11016 .$ What was the sum (In ₹) invested by Raghu in Scheme $X ?$