Answer
$12285$
Work Step by Step
The general formula to find the nth partial sum of a Geometric sequence is given as: $ S_{n}=\dfrac{a(1-r^n)}{(1-r)}$
$ r=\dfrac{a_2}{a_1}=\dfrac{6}{3}=2$ and $ n=12$
Now, $ S_{n}=\dfrac{3(1-(2)^{12})}{(1-2)}=3 \times \dfrac{-4095}{-1}$
Our answer is: $ S_{n}=12285$
