In a certain number of years,a sum of money doubles itself at $6 \frac{1}{4} \%$ simple interest per annum. The required time (in $years$) is:

There is a $60 \%$ increase in an amount in $6$ years at simple interest. What will be the compound interest (in ₹) of ₹ $12000$ after $3$ years at the same rate?

Abhinav invested a certain amount at the rate of $8$ $p.c.p.a.$ for $5$ years and obtained a $SI$ of $Rs. 3800$. Had he invested the same amount at the same interest rate for $2$ years,how much amount (in $Rs.$) would he have obtained as $CI$ at the end of $2$ years?

The simple interest accrued on an amount of $Rs. 20000$ at the end of $3$ years is $Rs. 7200$. What would be the compound interest accrued on the same amount at the same rate in the same period?

The difference between the simple interest and the compound interest (in ₹) on ₹ $600$ for $1$ year at $10 \%$ per annum,reckoned half-yearly is

On a certain sum of money,the simple interest for $2$ years is ₹ $200$ at the rate of $7 \%$ per annum. Find the difference between compound interest $(CI)$ and simple interest $(SI)$. (In ₹)