Vidyalelo
Aptitude · Q98

Compound Interest

Competitive Exams · Aptitude · question 98

Q98

At what rate of compound interest per annum will a sum of Rs. 1200 become Rs. 1348.32 in 2 years ?

A.
6.5%
B.
4.5%
C.
6%
Answer
D.
7.5%

Answer: Option C

Solution

Answer: Option C
Solution:
\begin{aligned} & {\text{A = P }}{\left( {1 + \frac{{\text{R}}}{{100}}} \right)^n} \\ & \Rightarrow 1348.32 = 1200{\left( {1 + \frac{{\text{R}}}{{100}}} \right)^2} \\ & \Rightarrow \frac{{134832}}{{120000}} = {\left( {1 + \frac{{\text{R}}}{{100}}} \right)^2} \\ & \Rightarrow \frac{{231525}}{{200000}} = {\left( {1 + \frac{{\text{R}}}{{100}}} \right)^2} \\ & \Rightarrow \frac{{2809}}{{2500}} = {\left( {1 + \frac{{\text{R}}}{{100}}} \right)^2} \\ & \Rightarrow {\left( {\frac{{53}}{{50}}} \right)^2} = {\left( {1 + \frac{{\text{R}}}{{100}}} \right)^2} \\ & \Rightarrow \frac{{53}}{{50}} = 1 + \frac{{\text{R}}}{{100}} \\ & \Rightarrow {\text{R}} = {\text{ 6% }} \\\end{aligned}