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- Quantitative Aptitude
6.Interest
hard
Sonika invested an amount of ₹ $5800$ for $2$ years. At what rate of compound interest (In $\% p.a.$) will she get an amount of ₹ $594.50$ at the end of two years?
A
$5$
B
$4$
C
$6$
D
$8$
Solution
(a) $SI =P\left[\left(1+\frac{r}{100}\right)^{t}-1\right]$
$\Rightarrow \quad 594.5=5800\left[\left(1+\frac{r}{100}\right)^{2}-1\right]$
$\Rightarrow \frac{594.5}{5800}+1=\left(1+\frac{r}{100}\right)^{2}$
$\Rightarrow \quad \frac{6394.5}{5800}=\left(1+\frac{r}{100}\right)^{2}$
$\Rightarrow \frac{r}{100}=1.05-1$
$\Rightarrow \quad \frac{r}{100}=0.05 \Rightarrow r=5 \%$
Standard 13
Quantitative Aptitude
