On a certain principal,if the simple interest for two years is ₹ $1400$ and the compound interest for two years is ₹ $1449$,what is the rate of interest (in $\%$) ?

Find the compound interest on $Rs. 12500$ at $8 \%$ per annum for $9$ months compounded quarterly (in $Rs.$).

The simple interest accrued on a certain principal is ₹ $2,000$ in five years at the rate of $4$ percent $p.a.$ What would be the compound interest (in ₹) accrued on the same principal at the same rate in two years?

$A$ sum of money at compound interest doubles itself in $15$ years. It will become eight times of itself in (in $years$):

If the rate of interest is $4 \%$ per annum for the first year,$5 \%$ per annum for the second year,and $6 \%$ per annum for the third year,then the compound interest on $Rs. 10000$ for $3$ years will be (in $Rs.$):

If the amount is $6 \frac{1}{4}$ times the principal after $2$ years at compound interest,the rate of interest (in $\%$) per annum is