$A$ sum invested at $5 \%$ simple interest per annum grows to ₹ $504$ in $4$ years. The same amount at $10 \%$ simple interest per annum in $2 \frac{1}{2}$ years will grow to (in ₹):

Rashmi lent $Rs. 600$ to Geeta for $2 \,yr$ and $Rs. 150$ to Seeta for $4 \,yr$ at the same rate of interest and received altogether $Rs. 80$ as simple interest from both. Find the rate of interest (in $\%$).

$A$ sum of money will double itself in $16$ years at simple interest at an yearly rate of (in $\%$):

Mr. Thomas invested an amount of $Rs. 13,900$ divided in two different schemes $A$ and $B$ at the simple interest rate of $14 \%$ $p.a.$ and $11 \%$ $p.a.$ respectively. If the total amount of simple interest earned in $2$ $years$ be $Rs. 3508$,what was the amount (in $Rs.$) invested in Scheme $B$?

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