Find the difference between $S.I.$ and $C.I.$ (in $Rs.$) at $14 \%$ per annum for $2$ years on a principal of $Rs. 10000$.

If the compound interest on a certain sum for $2$ years is ₹ $60.60$ and the simple interest is ₹ $60$,then the rate of interest per annum (in $\%$) is

What is $C.I.$ (in $Rs.$) on $Rs. 7500$ for $4$ years if the rate of interest is $10 \%$ p.a. for the first $2$ years and $20 \%$ p.a. for the next $2$ years?

What sum of money (in ₹) at compound interest will amount to ₹ $650$ at the end of the first year and ₹ $676$ at the end of the second year?

How many statements are required to find 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 ₹ $3,000$.

$A$ sum of money placed at compound interest doubles itself in $4$ $years$. In how many $years$ will it amount to four times itself?