Sequence And Series Question 587
Question: If the ratio of the sum of first three terms and the sum of first six terms of a G.P. be 125 : 152, then the common ratio r is
Options:
A) $ \frac{3}{5} $
B) $ \frac{5}{3} $
C) $ \frac{2}{3} $
D) $ \frac{3}{2} $
Show Answer
Answer:
Correct Answer: A
Solution:
Here $ \frac{S_3}{S_6}=\frac{125}{152}\Rightarrow \frac{a(r^{3}-1)/(r-1)}{a(r^{6}-1)/(r-1)}=\frac{125}{152} $
$ \Rightarrow $ $ (r^{3}-1)152=125(r^{6}-1)\Rightarrow r^{3}=\frac{27}{125}\Rightarrow r=\frac{3}{5} $ .
BETA
