$Rs. 600$ 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 $Rs.$)?

Prakash lends a part of ₹ $20,000$ at $8 \%$ simple interest and the remaining at $\frac{4}{3} \%$ simple interest. His total income after a year was ₹ $800$. Find the sum (in ₹) lent at $8 \%$ interest.

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

If the simple interest on ₹ $x$ at a rate of $a \%$ for $m$ years is same as that on ₹ $y$ at a rate of $a^2 \%$ for $m^2$ years,then $x: y$ is equal to

If a sum of money at simple interest doubles itself in $6$ years,it will become four times in how many years?

$A$ man took a loan from a bank at the rate of $12 \%$ $p.a.$ simple interest. After $3$ $years$ he had to pay ₹ $5400$ interest only for the period. The principal amount (in ₹) borrowed by him was: