A GaAs single crystal is grown by the Bridgman technique for production of p-type GaAs wafers doped with 0.6 ppm Mg. The equilibrium partition coefficient of Mg is 0.1. Determine the effective segregation coefficient that at least 65% of the single crystal is within 0.05 ppm of the 0.6 ppm target value when the melt contains 0.65 ppm Mg.).