  A recent proposal in which the equation of state of a polydisperse
hard-sphere mixture is mapped onto that of the one-component fluid is
extrapolated beyond the freezing point to estimate the jamming packing fraction
$\phi_\text{J}$ of the polydisperse system as a simple function of
$M_1M_3/M_2^2$, where $M_k$ is the $k$th moment of the size distribution. An
analysis of experimental and simulation data of $\phi_\text{J}$ for a large
number of different mixtures shows a remarkable general agreement with the
theoretical estimate. To give extra support to the procedure, simulation data
for seventeen mixtures in the high-density region are used to infer the
equation of state of the pure hard-sphere system in the metastable region. An
excellent collapse of the inferred curves up to the glass transition and a
significant narrowing of the different out-of-equilibrium glass branches all
the way to jamming are observed. Thus, the present approach provides an
extremely simple criterion to unify in a common framework and to give coherence
to data coming from very different polydisperse hard-sphere mixtures.
