Sequence And Series Question 498
Question: If the sum of the first 2n terms of $ 2,,5,,8… $ is equal to the sum of the first n terms of $ 57,,59,,61… $ , then n is equal to
[IIT Screening 2001]
Options:
A) 10
B) 12
C) 11
D) 13
Show Answer
Answer:
Correct Answer: C
Solution:
Given, $ \frac{2n}{2}{2.2+(2n-1)3}=\frac{n}{2}{2.57+(n-1)2} $ or $ 2(6n+1)=112+2n $ or $ 10n=110,,\therefore n=11 $ .
BETA
