An amount of money at compound interest grows up to $Rs. 3840$ in $4$ $years$ and up to $Rs. 3936$ in $5$ $years$. Find the rate of interest (in $\%$)?

The difference between the $S.I.$ and $C.I.$ obtained on a principal amount at $5$ $p.c.p.a.$ after $2$ years is $Rs. 35$. What is the principal amount (in $Rs.$)?

$A$ man borrows $Rs. 5100$ to be paid back with compound interest at the rate of $4 \%$ p.a. by the end of $2$ years in two equal yearly instalments. How much (in $Rs.$) will be each instalment?

If the difference between the compound interest and simple interest on a sum of money for $3$ years is ₹ $186$,find the sum of money (in ₹) if the rate of interest in both cases is $10 \%$.

$A$ sum of money doubles in $3$ years at compound interest,compounded annually. It will become $4$ times of itself in: (in $years$)

What would be the $C.I.$ on $Rs. 17500$ at the rate of $12$ $p.c.p.a.$ after $2$ years (in $Rs.$)?