In a certain number of years,a sum of money doubles itself at $6 \frac{1}{4} \%$ simple interest per annum. The required time (in $years$) is:

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 ₹).

The production of a factory grows at a $8 \%$ $p.a.$ What will be its production (in $lakh$ tonnes) for the year $2010$,if its production in $2008$ was $70$ $lakh$ tonnes?

$A$ sum of money at compound interest amounts in two years to Rs. $2809,$ and in three years to Rs. $2977.54.$ Find the rate of interest and the original sum.

$A$ sum of ₹ $3,200$ invested at $10 \%$ per annum compounded quarterly amounts to ₹ $3,362$. Compute the time period (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 $B$?