Question

find the sum, $s_n$, for the arithmetic series described? remember to use the formula $s_n = \frac{n}{2}(a_1 + a_n)$ where $a_1=8$, $a_n=79$, $n=6$ \
\
\bigcirc a. $s_n=522$ \
\bigcirc b. $s_n=213$ \
\bigcirc c. $s_n=261$ \
\bigcirc d. $s_n=498$

Explanation:

Step1: Substitute given values

Substitute $a_1=8$, $a_n=79$, $n=6$ into $S_n=\frac{n}{2}(a_1+a_n)$:
$S_6=\frac{6}{2}(8+79)$

Step2: Simplify the expression

First calculate $\frac{6}{2}=3$ and $8+79=87$:
$S_6=3\times87$

Step3: Compute final product

Multiply to get the result:
$S_6=261$

Answer:

c. $S_n$=261