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

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 $\%$) ?

A sum of money invested at compound interest amounts to ₹ $800$ in $3$ years and to ₹ $840$ in 4 years. The rate of interest (In $\%$) per annum is

Sam invested ₹ $15000$ at $10 \%$ per annum for one year. If the interest is compounded halfyearly, then the amount (In ₹) received by Sam at the end of the year will be

A certain sum at compound interest amounts in two years to ₹ $2809$ and in three years to ₹ $2977.54 .$ Find the rate of interest and the original sum (In ₹).

How many statements are useful for find this : 

What is the rate of interest percent $p.a.$?

$Statements:$

$I$. The difference between the compound interest and simple interest earned in two years on the amount invested is ₹ $100$.

$II$. The amount becomes ₹ $19,500$ in three years on simple interest.

$III$.The simple interest accrued in two years on the same amount at the same rate of interest is ₹ $3,000$.