Quantitative Aptitude Ques 1747
Question: Which term of the series $ 8+1.6+32+… $ is $ 0.00256 $ ?
Options:
A) 5
B) 7
C) 9
D) 6
Show Answer
Answer:
Correct Answer: D
Solution:
- $ a=8 $
$ \Rightarrow $ $ r=\frac{1.6}{8}=\frac{1}{5} $ Let 0.00256 be the nth term.
$ \therefore $ $ T _{n}=a{r^{(n-1)}} $
$ \Rightarrow $ $ 0.00256=8\times {{( \frac{1}{5} )}^{n-1}} $
$ \Rightarrow $ $ {{( \frac{1}{5} )}^{n-1}}=0.00032 $
$ \Rightarrow $ $ {{( \frac{1}{5} )}^{n-1}}=\frac{32}{100000} $
$ \Rightarrow $ $ {{( \frac{1}{5} )}^{n-1}}={{( \frac{1}{5} )}^{5}} $
$ \therefore $ $ n-1=5 $
$ \Rightarrow $ $ n=6 $
BETA
