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

In simple interest rate per annum,a certain sum amounts to ₹ $5,182$ in $2$ $years$ and ₹ $5,832$ in $3$ $years$. The principal in rupees is:

The simple interest on a sum of money will be ₹ $600$ after $10$ $years$. If the principal is trebled after $5$ $years$,then what will be the total interest (in ₹) at the end of the tenth year?

$A$ man buys a watch for ₹ $1950$ in cash and sells it for ₹ $2200$ at a credit of $1$ $year$. If the rate of interest is $10 \%$ $p.a.$,what is his profit or loss?

Peter invested an amount of ₹ $12,000$ at the rate of $10 \%$ $p.a.$ simple interest and another amount at the rate of $20 \%$ $p.a.$ simple interest. The total interest earned at the end of one year on the total amount invested became $14 \%$ $p.a.$ Find the total amount (in ₹) invested.

The annual instalment that will discharge a debt of ₹ $4200$ due in $5$ years at $10 \%$ simple interest (in ₹) is: