The sum of third and ninth term of an A.P is 8. Find the sum of the first 11 terms of the progression.
A. 44 B. 22 C. 19 D. 46 Answer: Option AShow Answer
Solution(By Apex Team)
The third term $t_{3}=a+2 d$
The ninth term $t_{9}=a+8 d$
$t_{3}+t_{9}=2 a+10 d=8$
Sum of first 11 terms of an AP is given by
$\begin{aligned}&\Rightarrow S_{11}=\frac{11}{2}[2a+10d]\\
&\Rightarrow S_{11}=\frac{11}{2}\times8\\
&\Rightarrow S_{11}=44\end{aligned}$
Related Questions On Progressions
How many terms are there in 20, 25, 30 . . . . . . 140?
A. 22B. 25
C. 23
D. 24
Find the first term of an AP whose 8th and 12th terms are respectively 39 and 59.
A. 5B. 6
C. 4
D. 3
Find the 15th term of the sequence 20, 15, 10 . . .
A. -45B. -55
C. -50
D. 0
The sum of the first 16 terms of an AP whose first term and third term are 5 and 15 respectively is
A. 600B. 765
C. 640
D. 680
HI 
EN