The difference between simple interest and compound interest on a certain sum for $3$ years at $5 \%$ per annum is ₹ $122$. Find the sum (in ₹).

Divide $Rs. 2602$ between $X$ and $Y$,so that the amount of $X$ after $7 \,yr$ is equal to the amount of $Y$ after $9 \,yr$,the interest being compounded at $4 \%$ per annum.

$A$ sum of ₹ $15000$ deposited at compound interest becomes double after $5$ $years$. After $20$ $years$,it will become (in ₹):

What will be the amount (in ₹) if a sum of ₹ $5000$ is placed at compound interest for $3$ years,while the rate of interest for the first,second,and third years is $2\%$,$3\%$,and $4\%$ per annum,respectively?

What will be $C.I.$ (in $Rs.$) on an amount of $Rs. 10000$ at the rate of $20$ $p.c.p.a.$ in two years if the interest rate is compounded half-yearly?

What would be the $C.I.$ on $Rs. 17500$ at the rate of $12$ $p.c.p.a.$ after $2$ years (in $Rs.$)?