$A$ sum of money at compound interest doubles itself in $15$ years. It will become eight times of itself in (in $years$):

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:

Aditya invested a certain amount in two different schemes $A$ and $B$. Scheme $A$ offers $S.I.$ at $12$ $p.c.p.a.$ and scheme $B$ offers $C.I.$ at $10$ $p.c.p.a.$ The interest accrued on the amount invested in scheme $A$ in $2$ years was $Rs. 3600$ and the total amount invested was $Rs. 35000$. What was the interest accrued on the amount (in $Rs.$) invested in scheme $B$?

On a certain principal,if the simple interest for two years is ₹ $1400$ and the compound interest for two years is ₹ $1449$,what is the rate of interest (in $\%$) ?

$A$ sum of $Rs. 8448$ is to be divided between $X$ and $Y$ who are respectively $18$ and $19 \,yr$ old,in such a way that if their shares be invested at $6.25 \%$ per annum at compound interest,they will receive equal amounts on attaining the age of $21 \,yr$. The present share of $X$ is (In $Rs.$)

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?