$A$ 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 $\%$)?

In how many years will a sum of money treble itself at $10 \%$ per annum simple interest?

What is the present worth (in ₹) of ₹ $132$ due in $2$ years at $5\%$ simple interest per annum?

Mr. Mani invested an amount of ₹ $12000$ at a simple interest rate of $10 \%$ $p.a.$ and another amount at a simple interest rate of $20 \%$ $p.a.$. The total interest earned at the end of one year on the total amount invested was $14 \%$ $p.a.$. Find the total amount (in ₹) invested.

If the simple interest on a certain sum of money is ₹ $256$ and the rate of interest per annum equals the number of years,then the rate of interest (in $\%$) is:

If ₹ $1000$ is invested at an interest rate of $5 \%$ and the interest is added to the principal every $10$ years,then the number of years in which it will amount to ₹ $2000$ is: