The mixed cold-hot dark matter cosmological model ( CHDM ) with \Omega _ { tot } = 1 and a falling power-law initial spectrum of Gaussian adiabatic perturbations ( n > 1 ) is tested using recent obserbational data . It is shown that its fit to the data becomes worse with the growth of n - 1 , and may be considered as unreasonable for n > 1.1 for all possible values of the Hubble constant . Thus , the CHDM model with a falling initial spectrum is worse than the same model with the approximately flat ( |n - 1 | < 0.1 ) spectrum . On the other hand , the CHDM model provides a rather good fit to the data if n lies in the range ( 0.9 - 1.0 ) , the Hubble constant H _ { 0 } < 60 km/s/Mpc ( H _ { 0 } < 55 for n = 1 ) and the neutrino energy density \Omega _ { \nu } < 0.25 . So , the CHDM model provides the best possibility for the realization of the simplest variants of the inflationary scenario having the effective slope n \approx ( 0.95 - 0.97 ) between galaxy and horizon scales , including a modest contribution of primordial gravitational wave background to large-angle \Delta T / T fluctuations of the cosmic microwave background ( resulting in the increase of their total rms amplitude by ( 5 - 10 ) \% ) expected in some variants . A classification of cosmological models according to the number of fundamental parameters used to fit observational data is presented , too .