Question

(Find the sum of the arithmetic series 31 + 37 + 43 + 49 + ... where n=8.

Answer 1

Explanation:

$\begin{gathered} Formula\text{ for the sum of an arithmetic series:} \\ S_n\text{ = }\frac{n}{2}(2a\text{ + \lparen n-1\rparen d\rparen} \end{gathered}$

a = the first term = 31

n =8

d = T3-T2 = 43 -37

= 6

$\begin{gathered} S_8\text{ = }\frac{8}{2}(2(31)\text{ +\lparen8-1\rparen *6\rparen} \\ \text{ = 416} \end{gathered}$

Answer: B