Quantitative Aptitude Ques 1940

Question: A sum of Rs. 12000 deposited at compound interest becomes double after 5 yr. After 20 yr, it will become

Options:

A) Rs. 48000

B) Rs. 96000

C) Rs. 190000

D) Rs. 192000

Show Answer

Answer:

Correct Answer: D

Solution:

  • Given, P=12000, then $ A=P{{( 1+\frac{r}{100} )}^{t}} $

$ \Rightarrow $ $ \frac{A}{P}={{( 1+\frac{r}{100} )}^{t}} $
$ \Rightarrow $ $ 2={{( 1+\frac{r}{100} )}^{5}} $ On squaring twice both sides, we get $ 2^{4}={{( 1+\frac{r}{100} )}^{20}} $
$ \Rightarrow $ $ 16={{( 1+\frac{r}{100} )}^{20}} $ Hence, the principal will become 16 times, i.e. $ Rs\text{. (16}\times \text{12000)= Rs}\text{. 192000} $