The difference between compound and simple interest at a certain rate on $Rs. 2000$ at the end of two years is $Rs. 12.8$. The rate of interest (in $\%$) per annum is:

Which information given below is sufficient to know the principal amount if the difference between the $C.I.$ and $S.I.$ for $2$ years is $18$?
$(I)$ The rate is same at which an amount of $Rs. 1000$ becomes $1120$ in $2$ years under $S.I.$
$(II)$ The principal is $Rs. 2000$.

What would be the $C.I.$ obtained on an amount of $Rs. 12000$ at the rate of $9 \,p.c.p.a$ for $3$ years (in $Rs.$)?

$A$ certain sum of money (in $Rs.$) gives $Rs. 500$ as Simple Interest $(S.I.)$ at $5 \%$ per annum for $1$ year. What is the Compound Interest $(C.I.)$ on the same sum at the same rate at the end of $2$ years?

What would be the $C.I.$ obtained on an amount of $Rs. 4800$ at the rate of $5$ $p.c.p.a$ for $3$ years (in $Rs.$)?

$A$ sum of $Rs. 1000$ after $3 \, \text{years}$ at compound interest becomes a certain amount that is equal to the amount that is the result of a $3 \, \text{year}$ depreciation from $Rs. 1728$. Find the difference between the rates (in $\%$) of $C.I.$ and depreciation? (Given $C.I.$ is $10 \% \, p.a.$)