In the given figure, two wheels \( P \) and \( Q \) are connected by a belt \( B \). The radius of \( P \) is three times as that of \( Q \). In case of same rotational kinetic energy, the ratio of rotational inertias \( \left( \dfrac{I_{1}}{I_{2}} \right) \) will be \( x : 1 \). The value of \( x \) will be ________.
