Question

what is the value of r of the geometric series?
\\(\sum_{n=1}^{3} 1.3(0.8)^{n - 1}\\)

• 0.8
• 1.3
• 3.0
• 3.2

Explanation:

Step1: Recall Geometric Series Formula

The general form of a geometric series is $\sum_{n = 1}^{\infty} a(r)^{n - 1}$, where $a$ is the first - term and $r$ is the common ratio.

Step2: Compare with Given Series

The given series is $\sum_{n = 1}^{3}1.3(0.8)^{n - 1}$. By comparing it with the general form $\sum_{n = 1}^{N}a(r)^{n - 1}$, we can see that $a = 1.3$ and $r=0.8$.

Answer:

A. 0.8