If the simple interest on a certain sum of money after $6 \frac{1}{4}$ years is $\frac{3}{8}$ of the principal,then the rate of interest (in $\%$) per annum is

$A$ sum of money invested at simple interest for two years at $5 \% \text{ p.a.}$ amounted to $Rs. 2750$. The rate at which the sum should have been invested to get $Rs. 300$ as interest after two years would be (in $\%$)?

$A$ sum of money becomes $\frac{8}{5}$ of itself in $5$ $years$ at a certain rate of interest. The rate per cent per annum is

$A$ sum of $Rs. 15000$ amounts to an interest of $Rs. 4500$ in $5$ years. What is the rate of interest (in percentage)?

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

With a given rate of simple interest,the ratio of principal and amount for a certain period of time is $4:5$. After $3$ years,with the same rate of interest,the ratio of the principal and amount becomes $5:7$. The rate of interest per annum is (in $\%$):