Quantitative Aptitude Ques 377

Question: The compound interest on Rs. 30000 at 7% per annum for a certain time a Rs. 4347. The time is

[IBPS (Office Assistant) 2015]

Options:

A) 2 yr

B) 2.5 yr

C) 3 yr

D) 4 yr

E) None of these

Show Answer

Answer:

Correct Answer: A

Solution:

  • $ CI=P{{( 1+\frac{r}{100} )}^{n}}-P $

$ \Rightarrow $ $ 4347=30000{{( 1+\frac{7}{100} )}^{n}}-30000 $

$ \Rightarrow $ $ 4347=30000[ {{( 1+\frac{7}{100} )}^{n}}-1 ] $

$ \Rightarrow $ $ 4347=30000[ {{( \frac{107}{100} )}^{n}}-1 ] $

$ \Rightarrow $ $ \frac{4347}{30000}=[ {{( \frac{107}{100} )}^{n}}-1 ] $

$ \Rightarrow $ $ \frac{4347}{30000}+1={{( \frac{107}{100} )}^{n}} $
$ \Rightarrow $ $ \frac{34347}{30000}={{( \frac{107}{100} )}^{n}} $

$ \Rightarrow $ $ \frac{11449}{10000}={{( \frac{107}{100} )}^{n}} $
$ \Rightarrow $ $ {{( \frac{107}{100} )}^{n}}={{( \frac{107}{100} )}^{n}} $

$ \therefore $ $ n=2,yr $