Answer
93 mH.
Work Step by Step
We are told that there is no current in the secondary of the transformer. In that case, there is no induced emf from the mutual inductance. In the primary, the ratio of the input voltage to the current is the inductive reactance, given by $X_L=2\pi fL$. Solve for the inductance.
$$\frac{V_{rms}}{I_{rms}}= X_L=2\pi fL $$
$$L=\frac{V_{rms}}{2\pi f I_{rms}}=\frac{220V}{2\pi (60.0Hz)(6.3A)}=9.3\times10^{-2}H$$
