Measurement of the charge ratio of cosmic ray muons in extensive air showers provides a means of investigating the phenomenon of East-West effect whereby more positively charged muons arrive on the Earth's surface from the West than the East. Although experimental observations have indicated the existence of this phenomenon, the data collected has been insufficient for studying in fine details the variation of the muon charge ratio with zenith angles. In this book, hadronic interaction models are used to probe the variation of the muon charge ratio within small ranges of zenith angles by simulation. The results confirm an East-West effect for inclined and low energy muons. The findings of this work should aid the developers of the hadronic interaction models used to fine-tune them so as to conform more to experimental data. It should also prove useful to researchers in astroparticle physics, where large volumes of data are collected, to countercheck their findings with the theoretically expected values.