Question

The compound interest on Rs. 8,000 at $20\%$ per annum for 9 months compounded quarterly is

• A. Rs. 1,260
• B. Rs. 1,261
• C. Rs. 1,271
• D. Rs. 1,281

Answer 1

The correct option is B Rs. 1,261

Here, P = Rs. 8,000, R$=20\%$ per annum, $n=9$ months
$=\frac{9}{12}year=\frac{3}{4}year$
$A=P{[1+\frac{R}{100}]}^{4n}=8000{[1+\frac{20}{400}]}^{4\times \frac{3}{4}}$
$=8000{\left[\frac{21}{20}\right]}^3$
$=8000\times \frac{21}{20}\times \frac{21}{20}\times \frac{21}{20}=9261$
$\therefore CI=A-P-=9261-8000=Rs.1261$