The difference between simple and compound interest compounded annually on a certain sum of money for $2$ years at $4 \%$ per annum is $Rs. 1$. The sum (in $Rs.$) is

The difference between compound interest and simple interest on a sum for $2$ years at $10 \%$ per annum,when the interest is compounded annually,is ₹ $20$. If the interest were compounded half-yearly,the difference in the two interests (in ₹) will be:

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 ₹ $1260$ is borrowed from a money lender at $10 \%$ p.a. compounded annually. If the amount is to be paid back in two equal annual instalments,find out the annual instalment (in ₹).

$A$ bank offers $5 \%$ compound interest calculated on a half-yearly basis. $A$ customer deposits ₹ $1600$ each on $1^{st}$ January and $1^{st}$ July of a year. At the end of the year,the amount (in ₹) he would have gained by way of interest is

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