$A$ sum of money lent out at simple interest amounts to $Rs. 720$ after $2$ years and $Rs. 1020$ after a further period of $5$ years. Find the principal (in $Rs.$).

Prabhat took a certain amount as a loan from a bank at the rate of $8 \%$ simple interest per annum and gave the same amount to Ashish as a loan at the rate of $12 \%$ per annum on simple interest. If at the end of $12$ years,he made a profit of $Rs. 320$ in the deal,what was the original amount (in $Rs.$)?

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

The principal (in ₹) that will yield ₹ $60$ as simple interest at $6 \%$ per annum in $5$ years is

$Rs. 600$ becomes $Rs. 720$ in $4$ $years$ at simple interest. If the rate of interest is increased by $2 \%$,what will be the total amount (in $Rs.$)?

Arun invested a sum of money at a certain rate of simple interest for a period of $4$ years. Had he invested the same sum for a period of $6$ years,the total interest earned by him would have been $50$ percent more than the earlier interest amount. What was the rate of interest per cent per annum?