Identifying a multiple secondary unknown transformer
I think the "impedance" measurement is misleading the results. The formula you are using relates the ratio of voltage to the square of the ratio of inductance, not impedance. And you have not calculated the inductance of the individual coils. This impedance is the vector of the inductance and series resistance. Try taking some measurements and calculating the inductance and resistance independently, if their vector becomes your impedance measurement, my hypothesis is correct.