If a sum of money placed at compound interest,compounded annually,doubles itself in $5$ years,then the same amount of money will be $8$ times of itself in how many years?

$A$ certain sum of money invested at compound interest becomes $1.44$ times of itself in $2$ years. If twice this sum were lent at simple interest, in how many years would it double itself?

The simple interest accrued on an amount of $Rs. 19800$ at the end of $3$ years is $Rs. 7128$. What would be the compound interest (in $Rs.$) accrued on the same amount at the same rate in the same period?

$A$ 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 ₹).

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:

The difference between the simple and compound interest on a certain sum of money for $2$ years at $4 \%$ per annum is $Rs. 4$. Find the sum (In $Rs.$)?