How do you find the sum of the infinite geometric series given $3+1.8+1.08+...$ ?

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Answer 1 · 2016-10-12T13:30:00

The series has a sum of $7.5$ .

We use the formula $s_oo = a/(1 - r)$ to determine the sum of an infinite convergent geometric series.

In other words, for us to be able to find the sum, $|r| < 1$ .

We can find $r$ by using the formula $r = t_2/t_1$ .

$r = t_2/t_1$

$r = 1.8/3$

$r = 0.6$

We now know $a$ , which is $3$ and $r$ , which is $0.6$ .

$s_oo = 3/(1 - 0.6)$

$s_oo = 3/0.4$

$s_oo = 7.5$

Hopefully this helps!

How do you find the sum of the infinite geometric series given 3+1.8+1.08+...3+1.8+1.08+...?