Answer
$\dfrac{9}{4}$
Work Step by Step
The general formula to find the sum of an infinite Geometric series is given as:
$ S_{n}=\dfrac{a_1}{(1-r)}$
and $ r=\dfrac{a_2}{a_1}=\dfrac{-1}{3}=\dfrac{-1}{3}$
Now, $ S_{n}=\dfrac{a_1}{(1-r)}=\dfrac{3}{1-(-\dfrac{1}{3})}$
Our answer is: $ S_{n}=\dfrac{3}{3/4}=\dfrac{9}{4}$
