$A$ sum of money doubles in $3$ years at compound interest,compounded annually. It will become $4$ times of itself in: (in $years$)

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 $B$?

What would be the $C.I.$ obtained on an amount of $12500$ at the rate of $12 \, p.c.p.a.$ after $2$ years (in $Rs.$)?

In how many years will a sum of ₹ $800$ at $10 \%$ per annum compounded semi-annually become ₹ $926.10$?

What sum of money (in ₹) at compound interest will amount to ₹ $650$ at the end of the first year and ₹ $676$ at the end of the second year?

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