Quantitative Aptitude Ques 2070
Question: A sum of money becomes eight times in 3 yr, if the rate is compounded annually. In how much time will the same amount at the same compound rate become sixteen times?
Options:
A) 6 yr
B) 4 yr
C) 8 yr
D) 5 yr
Show Answer
Answer:
Correct Answer: B
Solution:
- Let the principal be Rs. 1. Then, amount is Rs. 8. Now, $ A=P{{( 1+\frac{r}{100} )}^{T}} $
$ \Rightarrow $ $ 8=1{{( 1+\frac{r}{100} )}^{3}} $
$ \Rightarrow $ $ 2^{3}={{( 1+\frac{r}{100} )}^{3}} $
$ \Rightarrow $ $ 2={{( 1+\frac{r}{100} )}^{1}} $
On squaring twice both sides, we get
$ 2^{4}={{( 1+\frac{r}{100} )}^{4}} $
$ \therefore $ $ 16={{( 1+\frac{r}{100} )}^{4}} $ So, in 4 yr the same amount at the same compound rate become sixteen times
$ \therefore $ Time = 4 yr
BETA
