Probability

Events \(E_1\) and \(E_2\) from a partition of the sample space \(S\). \(A\) is any event such that \(P\left(E_1\right)=P\left(\dot{E}_2\right)=\frac{1}{2}, P\left(E_2 / A\right)=\frac{1}{2}\) and \(P\left(A / E_2\right)=\frac{2}{3}\), then \(P\left(E_1 / A\right)\) is