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

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 $Rs.$)?

Sita deposited $Rs. 5000$ at $10\%$ simple interest for $2$ years. How much more money (in $Rs.$) will Sita have in her account at the end of $2$ years,if it is compounded semi-annually?

What is the rate of interest (in $\%$) if simple interest earned on a certain sum for the $3^{rd}$ year is $₹ 2,000$ and compound interest earned in $2$ years is $₹ 4,160$?

If the compound interest on a certain sum of money for $2$ years is $Rs. 164$ whereas the simple interest for $3$ years at the same rate is $Rs. 240$ on the same sum,find the sum (in $Rs.$).

If the compound interest on a certain sum for $3$ years at $5 \%$ p.a. exceeds the simple interest on the same sum for the same time and at the same rate by $Rs. 183$,find the sum (in $Rs.$).