Predicted model IMFs of the three populations, colour coded as in Table 1. Upper row: IMFs assuming random sampling. The shaded regions indicate the one-sigma range for 10 000 realisations. Lower row: IMFs assuming nature follows optimal sampling. These have no uncertainties. The solid lines indicate the canonical IMF normalised to the empirical total stellar mass of all populations combined as given by Beccari et al. (2017), and the right dashed vertical lines depict m_max while the left vertical lines indicate 0.5 M_⊙. The thick grey solid lines are the canonical IMF normalised, as are the histograms, to the mass of each sub-population. Note that if the IMF is a probability distribution function (upper panels) then the distinct co-eval populations would on average contain a larger number of more-massive stars than if the IMF is an optimally sampled distribution function (lower panels).