Question

find the sum of the first ten terms of an arithmetic series if the first term is 3 and the last term is 39a. 190b.210c.230d.275

Answer 1

Given the first term is 3 and the last term is 39.

Recall that the sum is given as:

$S_n=\frac{n}{2}(a_1+a_n)$

Substituting in the above equation gives:

$\begin{gathered} S_n=\frac{10}{2}(3+39) \\ S_n=5(42) \\ S_n=210 \end{gathered}$

Therefore, option (a) is correct.