Answer
$=\dfrac {1}{11}$
Work Step by Step
$0.\overline {09}=0.090909...=\dfrac {9}{100}+\dfrac {9}{100^{2}}+\dfrac {9}{100^{3}}+...=\dfrac {a_{1}}{1-r}=\dfrac {\dfrac {9}{100}}{1-\dfrac {1}{100}}=\dfrac {\dfrac {9}{100}}{\dfrac {99}{100}}=\dfrac {9}{99}=\dfrac {1}{11}$