Resonance

A student is performing the resonance column experiment using a tube of diameter $4 \mathrm{cm}$ and a tuning fork of frequency $512 \mathrm{Hz}$. The air temperature is $38 °\mathrm{C}$ in which the speed of sound is $336 \mathrm{m} {\mathrm{s}}^{-1}$. The zero of the meter scale coincides with the top end of the resonance column tube. When the first resonance occurs, the reading of the water level in the column is