#### Answer

$\dfrac {3}{2}$

#### Work Step by Step

$r=\dfrac {\dfrac {1}{27}}{\dfrac {1}{9}}=\dfrac {\dfrac {1}{9}}{\dfrac {1}{3}}=\dfrac {\dfrac {1}{3}}{1}=\dfrac {1}{3};a_{1}=1\Rightarrow S_{\infty }=\dfrac {a_{1}}{1-r}=\dfrac {1}{1-\dfrac {1}{3}}=\dfrac {3}{2}$