Question

In an arithmetic series, $a_1=7$ and $a_{12}=29$. Find the sum of the first 12 terms.

• A. $116$
• B. $216$
• C. $316$
• D. $416$

Answer 1

Answer: (B)

$216$

Given:

First term: $a=7$
Last term, $l=29$

Here, $a_n=29$

and $n=12$

We know that $S_n=\frac{n}{2}[a+l]$

$\therefore S_{12}=\frac{12}{2}[7+29]$

$=6\times 36$

$=216$