If the difference between $S.I.$ and $C.I.$ is $Rs. 25$ on $10000$ for $2$ years,then what is the rate of interest (in $\%$)?

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 $₹ 4,160$?

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

If the compound interest on a sum for $2$ years at $12 \frac{1}{2} \%$ per annum is ₹ $510$,the simple interest (in ₹) on the same sum at the same rate for the same period of time is

$A$ sum of money placed at compound interest doubles itself in $5$ years. It will amount to eight times itself at the same rate of interest in (in $years$):

If the compound interest on a certain sum for $2$ years is ₹ $105$ and simple interest is ₹ $100$,then the sum (in ₹) is: