  In this work we examine with the help of Monte Carlo simulation whether a
consistent primary energy spectrum of cosmic rays emerges from both the
experimentally observed total charged particles and muon size spectra of cosmic
ray extensive air showers considering primary composition may or may not change
beyond the knee of the energy spectrum. It is found that EAS-TOP observations
consistently infer a knee in the primary energy spectrum provided the primary
is pure unchanging iron whereas no consistent primary spectrum emerges from
simultaneous use of the KASCADE observed total charged particle and muon
spectra. However, it is also found that when primary composition changes across
the knee the estimation of spectral index of total charged particle spectrum is
quite tricky, depends on the choice of selection of points near the knee in the
size spectrum.
