The least number of completed years in which a sum of money put out at $20 \%$ $C.I.$ will be more than doubled is

Find the compound interest (in ₹) on ₹ $15625$ for $9$ months at $16 \%$ per annum compounded quarterly.

There is a $40 \%$ increase in an amount in $8$ years at simple interest. What will be the compound interest (in rupees) on ₹ $30000$ after $2$ years at the same rate?

$A$ sum of ₹ $12,000$ deposited at compound interest becomes double after $5$ years. After $20$ years,it will become (in ₹): (in $,000$)

There is a $60 \%$ increase in an amount in $6$ years at simple interest. What will be the compound interest (in $Rs.$) on $Rs. 12,000$ after $3$ years at the same rate?

$A$ 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 $Rs.$)