The compound interest on ₹ $4000$ for $4$ years at $10 \%$ per annum will be (in ₹):

In a certain number of years,a sum of money doubles itself at $6 \frac{1}{4} \%$ simple interest per annum. The required time (in $years$) is:

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?

What is $C.I.$ (in $Rs.$) on $Rs. 7500$ for $4$ years if the rate of interest is $10 \%$ p.a. for the first $2$ years and $20 \%$ p.a. for the next $2$ years?

If the difference between $S.I.$ and $C.I.$ for $2$ years on a sum of money lent at $5 \%$ per annum is $₹ 6$,then the sum is:

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