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Aptitude · Q55

Compound Interest

Competitive Exams · Aptitude · question 55

Q55

An amount of Rs. 10000 becomes Rs. 14641 in 2 years if the interest is compounded half yearly. What is the rate of compound interest p.c.p.a. ?

A.
10%
B.
12%
C.
16%
D.
20%
Answer
E.
None of these

Answer: Option D

Solution

Answer: Option D
Solution:
\begin{aligned} & {\text{Let the rate be R% p}}{\text{.a}}{\text{. }} \\ & {\text{Then,}} \\ & {\text{10000}}{\left( {1 + \frac{{\text{R}}}{{2 \times 100}}} \right)^4} = 14641 \\ & \Rightarrow {\left( {1 + \frac{{\text{R}}}{{200}}} \right)^4} = \frac{{14641}}{{10000}} = {\left( {\frac{{11}}{{10}}} \right)^4} \\ & \Rightarrow 1 + \frac{{\text{R}}}{{200}} = \frac{{11}}{{10}} \\ & \Rightarrow \frac{{\text{R}}}{{200}} = \frac{1}{{10}} \\ & \Rightarrow {\text{R}} = {\text{20% }} \\\end{aligned}