Compound Interest Ques 16
Question
The compound interest on Rs. 30000 at 7% per annum for a certain time is Rs. 4347. The time is
(1) 2 yr
(2) 2.5 yr
(3) 3 yr
(4) 4 yr
(5) None of these
(IBPS (Office Assistant) 2015)
Show Answer
Correct Answer: (1)
Solution: (1)
$ 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 $
BETA
