The self-consistent effective-medium approximation is used to study the extraordinary magnetoresistance effect observed in nonmagnetic semiconductors. The inhomogeneous materials are treated as a three-dimensional resistor network of binary disorder, where the receptivity of each component is a tensor describing both the zero-field resistance and the Hall effect. The effective conductivity tensor of the total system is calculated with applied magnetic field. The resulting transversal magnetoresistance, longitudinal magnetoresistance and effective Hall coefficient are shown for different component concentrations and magnetic fields. When the components have two different types of charge carriers, and the mismatch between the zero-resistivity is enlarged, the macroscopic magnetoresisance exhibits complex behaviors which are related closely with the formation of the percolation structure in the inhomogeneous system.