- Home
- Standard 13
- Quantitative Aptitude
6.Interest
medium
If the compound interest on a certain sum of money for $2$ years at $5 \%$ is ₹ $328,$ then the sum (In ₹) is
A
$3000$
B
$3600$
C
$3200$
D
$3400$
Solution
(c) Let the principal be $₹ P$. Then, $CI =P\left[\left(1+\frac{R}{100}\right)^{2}-1\right]$
$\Rightarrow \quad 328=P\left[\left(1+\frac{5}{100}\right)^{2}-1\right]=P\left[\left(\frac{21}{20}\right)^{2}-1\right]$
$\Rightarrow \quad 328=P\left(\frac{441}{400}-1\right)=P\left(\frac{441-400}{400}\right)=P\left(\frac{41}{400}\right)$
$\Rightarrow P=\frac{328 \times 400}{41}=3200$
Standard 13
Quantitative Aptitude
