₹ $800$ becomes ₹ $956$ in $3$ $years$ at a certain rate of simple interest. If the rate of interest is increased by $4 \%,$ what amount (in ₹) will ₹ $800$ become in $3$ $years?$

$A$ took two loans altogether of ₹ $1200$ from $B$ and $C$. $B$ claimed $14 \%$ simple interest per annum,while $C$ claimed $15 \%$ per annum. The total interest paid by $A$ in one year was ₹ $172$. How much did $A$ borrow from $B$?

Divide ₹ $2379$ into $3$ parts so that their amounts after $2, 3$ and $4$ years respectively may be equal,the rate of interest being $5 \%$ per annum at simple interest. The first part is (in ₹):

If a sum of money at simple interest doubles itself in $6$ years,it will become four times in how many years?

Nitin borrowed some money at the rate of $6 \% \text{ p.a.}$ for the first three years,$9 \% \text{ p.a.}$ for the next five years,and $13 \% \text{ p.a.}$ for the period beyond eight years. If the total interest paid by him at the end of eleven years is ₹ $8,160$,the money borrowed by him was:

$A$ sum of money doubles itself in $8$ years. In how many years will it treble?