Question

During a period of two years, a principal of Rs. $100$ amounts to Rs. $121$ at the annual compount rate of $r\%$. The value of $r$ will be

• A. $9$
• B. $10$
• C. $\frac{21}{2}$
• D. $11$

Answer 1

Answer: (B)

$10$

Given, Sum (P) = Rs. 100,
Amount due (A) = Rs. 121
Time (n) = 2 years, Rate (r) = ?
We know $A=P(1+\frac{r}{100})$
$\therefore 121=100{(1+\frac{r}{100})}^2$
or ${(1+\frac{r}{100})}^2=\frac{121}{100}$
or $1+\frac{r}{100}=\frac{11}{10}=1+\frac{1}{10}=1+\frac{10}{100}$
$\therefore r=10$%