If ₹ $640$ amounts to ₹ $832$ in $2$ years,what will ₹ $860$ amount to in $4$ years at the same rate of interest per annum (in ₹)?

The population of a particular area of a city is $5000$. It increases by $10 \%$ in $1^{st} \,yr$. It decreases by $20 \%$ in the $2^{nd} \,yr$ because of some reason. In the $3^{rd} \,yr$ the population increases by $30 \%$. What will be the population of the area at the end of $3$ $years$?

$A$ money lender finds that due to a fall in the annual rate of interest from $8 \%$ to $7 \frac{3}{4} \%,$ his yearly income diminishes by ₹ $61.50$. His capital (in ₹) is:

The rate of interest on a sum of money is $4 \%$ per annum for the first $2$ years,$6 \%$ p.a. for the next $4$ years,and $8 \%$ p.a. for the period beyond $6$ years. If the simple interest accrued by the sum for a total period of $9$ years is ₹ $1120$,then the sum (in ₹) is:

The rate of interest on a sum is $4 \%$ per annum for the first $2$ years,$6 \%$ per annum for the next $4$ years,and $8 \%$ per annum for the period beyond $6$ years. If the simple interest accrued by the sum for a total period of $9$ years is ₹ $1120$,find the sum. (In ₹)

Prakash lends a part of ₹ $20,000$ at $8 \%$ simple interest and the remaining at $\frac{4}{3} \%$ simple interest. His total income after a year was ₹ $800$. Find the sum (in ₹) lent at $8 \%$ interest.