Sequence And Series Question 502
Question: $ 7^{th} $ term of an A.P. is 40, then the sum of first 13 terms is
[Karnataka CET 2003]
Options:
A) 53
B) 520
C) 1040
D) 2080
Show Answer
Answer:
Correct Answer: B
Solution:
$ 7^{th} $ term of an A.P. $ =40 $ $ a+6d=40 $ $ S_{13}=\frac{13}{2}[2a+(13-1)d]=\frac{13}{2}[2(a+6d)] $ $ =\frac{13}{2}\ .\ 2\ .\ 40=520 $ .
BETA
