What amount (in $Rs.$) would a man have received on a principal of $Rs. 4000$ after $2$ years at a simple interest rate of $5$ $p.c.p.a.$?

At what percent of simple interest will a sum of money double itself in $15$ years?

Deepak lent ₹ $8800$ to Jaichand for $13$ $years$ and ₹ $5500$ to another person for $12$ $years$ at the same rate of simple interest. He received ₹ $14432$ in total as interest from both. The rate of interest (in $\%$) per annum is:

$A$ man invested $\frac{1}{3}$ of his capital at $7 \%$,$\frac{1}{4}$ at $8 \%$,and the remainder at $10 \%$. If the annual income is ₹ $561$,the capital (in ₹) is:

$A$ certain sum is invested for $T$ years. It amounts to ₹ $400$ at $10 \%$ $p.a.$. But,when invested at $4 \%$ $p.a.$,it amounts to ₹ $200$. Find the time (in years) $(T)$.

Kavita invested $\frac{1}{3}$ of her money at $4 \% \text{ p.a.}$,$\frac{1}{4}$ at $3 \% \text{ p.a.}$,and the rest at $5 \% \text{ p.a.}$ She received an annual interest of $Rs. 500$ on her money. Find the total money invested (in $Rs.$).