In how many years will a sum of money treble itself at $10 \%$ per annum simple interest?

Nitin borrowed some money at the rate of $6 \% \text{ p.a.}$ for the first $3 \text{ years}$,$9 \% \text{ p.a.}$ for the next $5 \text{ years}$,and $13 \% \text{ p.a.}$ for the period beyond $8 \text{ years}$. If the total interest paid by him at the end of $11 \text{ years}$ is $₹ 8,160$,how much money (in $₹$) did he borrow?

$A$ sum of ₹ $16800$ is divided into two parts. One part is lent at a simple interest rate of $6 \%$ per annum and the other at $8 \%$ per annum. After $2$ years,the total amount received is ₹ $19000$. The sum lent at the rate of $6 \%$ simple interest (in ₹) is:

$A$ sum invested at $5 \%$ simple interest per annum grows to ₹ $504$ in $4$ years. The same amount at $10 \%$ simple interest per annum in $2 \frac{1}{2}$ years will grow to (in ₹):

If simple interest on a certain sum of money for $4$ years at $5 \%$ $p.a.$ is same as the simple interest on ₹ $560$ for $10$ years at the rate of $4 \%$ $p.a.$,then the sum of money (in ₹) is

$A$ man invests ₹ $3965$ in the names of his three daughters,Neeta,Sita,and Gita,in such a way that they would receive the same amount after $2, 3,$ and $4$ years. If the rate of interest is $5 \%$ p.a.,then the amount (in ₹) invested for Neeta,Sita,and Gita is: