Question

In an arithmetic series, find the sum of the first 10 terms if the first term is 3 and the common difference is 4.

• A. $110$
• B. $210$
• C. $310$
• D. $410$

Answer 1

The correct option is B $210$

First term = a = 3
n = 10
d = 4
$S_n=\frac{n}{2}[2a+(n-1\left)d\right]$
$S_{10}=\frac{10}{2}[2\times 3+(10-1\left)4\right]$
$S_{10}=5[6+36]$
$S_{10}=210$