Question:
Find the compound interest on Rs 8000 for 9 months at 20% per annum compounded quarterly.
Solution:
$\mathrm{P}=$ Rs 8,000
$\mathrm{~T}=9$ months $=3$ quarters
$\mathrm{R}=20 \%$ per annum $=5 \%$ per quarter
$\mathrm{A}=8,000\left(1+\frac{5}{100}\right)^{3}$
$=8,000(1.05)^{3}$
$=9,261$
The required amount is Rs 9,261 .
Now,
$\mathrm{CI}=\mathrm{A}-\mathrm{P}$
$=\mathrm{Rs} 9,261-\mathrm{Rs} 8,000$
$=\mathrm{Rs} 1,261$