Question

Find the compound interest on Rs.$20,000$ at $15$% per annum for $2\frac{1}{3}$ years.

Answer 1

Here, $P=$ $20,000$, $r=15$% p.a. and $n=2\frac{1}{3}$ years.
Amount after $2\frac{1}{3}$ years $=A=P{(1+\frac{r}{100})}^2[1+\frac{1}{3}\left(\frac{r}{100}\right)]$
$=20000{(1+\frac{15}{100})}^2[1+\frac{1}{3}\left(\frac{15}{100}\right)]$
$=20000{(1+\frac{3}{20})}^2(1+\frac{1}{20})$
$=20000{(1+\frac{23}{20})}^2\left(\frac{21}{20}\right)$
$=20000\times \frac{23}{20}\times \frac{23}{20}\times \frac{23}{20}$
$=$ $27,772.50$
C.I. $=A-P$
$=27,772.50-20,000$
$=$ $7,772.50$