Young populations vs. extreme horizontal branch stars. Top: Weights distribution measured for a synthetic spectrum combining a dominant old population (13 Gyr) and a 0.5% contribution from an SSP with ∼0.1 Gyr. Solid and dashed gray lines indicate the isochrones of the old and young populations, respectively. The recovered weights follow the tracks defined by both isochrones. Bottom: Similar weights distribution but for the combination of the same old population plus 40% of an SSP with an extreme horizontal branch. Again, solid and dashed gray lines indicate the theoretical isochrones used to build the models.