Consider a binary mixture of components A and B at temperature \( T \) and pressure \( P \). Let \( \vec{V}_A \) and \( \vec{V}_B \) be the partial molar volumes of A and B, respectively. At a certain mole fraction of A, \( X_A \):
\[ \left( \frac{\partial \vec{V}_A}{\partial X_A} \right)_{T,P} = 22 \text{ cm}^3 \text{ mol}^{-1} \quad \text{and} \quad \left( \frac{\partial \vec{V}_B}{\partial X_A} \right)_{T,P} = -18 \text{ cm}^3 \text{ mol}^{-1} \]
The value of \( X_A \), rounded off to 2 decimal places, is ____.