The interpretation of the EAS data relies on the employment
of hadronic interaction models, which are subject to theoretical and
experimental uncertainties that may hamper composition studies of
cosmic rays. To check the reliability of such models at the energies
relevant for EAS studies, the predictions of the models can be
compared with data from air shower observatories. In this regard,
the study of the number of muons becomes extremely useful, since
they are sensitive to the hadronic interactions that occur in the
early phases of the EAS development. In the paper, we propose a
Monte Carlo study to test the number of muons in hadronic
interaction models by the hybrid experiment (YAC-II + Tibet-III +
MD). For an air-shower event, the Tibet air-shower array (Tibet-III)
provides the arrival direction and the air-shower size which are
interrelated to primary energy, the Yangbajing Air shower Core
detector (YAC-II) array measures the high energy electromagnetic
particles in the very forward region so as to obtain the
characteristic parameters of air-shower cores, at the same time, the
underground MDs record the number of high-energy muons above
1 GeV. Since we can select proton events with high accuracy by
YAC-II almost independently of the hadronic interaction models, the
accompanying number of muons induced by proton events can be fed
out. With the unique settle of YAC-II, our results show that the
description of muon numbers in different hadronic interaction models
can be well systematics-checked to avoid the ambiguity of the
primary cosmic-ray mass composition around the knee energy region by
the Tibet hybrid experiment (YAC-II + Tibet-III + MD).