The amount of $I_3^{-}(aq)$ in a solution can be determined by titration with a solution containing a known concentration of $S_2{O}_3^{2-}(aq)($thiosulfate ion$).$ The determination is based on the net ionic equation

$2S_2{O}_3^{2-}(aq)+I_3^{-}(aq)longrightarrow{S}_4{O}_6^{2-}(aq)+3I^{-}(aq)$

Given that it requires $27\mathrm{.}9mL$ of $0\mathrm{.}400MN{a}_2{S}_2{O}_3(aq)$ to titrate a $30\mathrm{.}0m{L}^2$ sample of $I_3^{-}(aq),$ calculate the molarity of $I_3^{-}(aq)$ in the solution.

$[I_3^{-}]=$