Question

The rate of interest on a sum of money is $4$% per annum for the first $2$ years, $6$% per annum for the period next $4$ years, $8$% per annum for the period beyond $6$ years. If the simple interest accrued by the sum for a total period of $9$ years is Rs. $1680$, what is the sum?

Answer 1

We know that $SI=\frac{PRT}{100}$

$SI$ at the rate of $4$% for $2$ years = $\frac{P\times 4\times 2}{100}$

$=\frac{8P}{100}$

$SI$ at the rate of $6$% for $4$ years

$\frac{P\times 6\times 4}{100}=\frac{24P}{100}$

$SI$ for next $3$ years $SI=$ $\frac{P\times 8\times 3}{100}=\frac{24P}{100}$

Total $S.I=$ $\frac{8P}{100}+\frac{24P}{100}+\frac{24P}{100}$

$1680=\frac{56P}{100}$

$\Rightarrow P=\frac{1680\times 100}{56}=Rs.3,000$