Question

A sum of money invested at compound interest amounts to ₹ 19,360 in 2 years and to 23,425.60 in 4 years. Find the rate percent

• A. 7 %
• B. 7.5 %
• C. 8 %
• D. 10 %

Answer 1

The correct option is D

10 %

Amount in 2 years = ₹ 19360 = P$(1+\frac{r}{100}{)}^2$ _________(1)

Amount in 4 years = ₹ 23,425.60 = P$(1+\frac{r}{100}{)}^4$ ___________(2)
On dividing (2) by (1) , we get

$\left(\frac{P(1+\frac{r}{100}{)}^4}{P(1+\frac{r}{100}{)}^2}\right)$ = $\frac{23425.60}{19360}$

(1 +$\frac{r}{100}{)}^2$ = 1.21
$(\frac{100+r}{100}{)}^2$ = 1.21
$\left(\frac{100+r}{100}\right)$ = 1.1
100 + r = 110
r = 10 %