Chapter 12 Sequences and Series - 12.4 Find Sums of Infinite Geometric Series - 12.4 Exercises - Skill Practice - Page 823: 7

$10$

Here, we have $a_n= a_1 r^{n-1}$ for the Geometric series. First term $a_1= 8$ and Common ratio $r=\dfrac{1}{5}$ The sum of an infinite Geometric Series can be found using: $a_n=\dfrac{a_1}{1-r}$ Thus, $a_n=\dfrac{8}{1-(1/5)}=10$