This paper continues application of the Margules-based phase-equilibrium uncertainty method to systems with weak and strong deviations from Raoult's law. The method was developed in order to provide practicing engineers with an intuitive and easily applicable method to quantitatively relate process-design uncertainties to uncertainties in correlated physical properties, specifically nonideal phase equilibrium. The methodology has been used in several case studies: (1) a propylene + propane superfractionator for which small changes in correlated relative volatilities have a large effect on the design of the distillation column; (2) a dehexanizer column that separates a mixture containing many close-boiling hydrocarbon components; (3) a distillation train that separates the acetone + chloroform + benzene ternary mixture, which contains one maximum-boiling azeotrope; and (4) separation of the water + 1-butanol binary mixture, which has a heterogeneous azeotrope. The present work applies the methodology to the purification of ethyl acetate from a ternary mixture with ethanol and water. This purification step occurs in the production of ethyl acetate via esterification of acetic acid with ethanol, and the process design is complex because the ethyl acetate + ethanol + water ternary mixture exhibits a liquid liquid region and four azeotropes.