= Conditional evolved-companion fraction in a coeval binary population
{title2=$\mathbb E[g^2+2gw]/\mathbb E[2g-g^2]$}
= Evolved-companion fraction
{synonym}
If $g(t)$ is the conditional giant fraction and $w(t)$ a second evolved-state fraction at common age $t$, independent component masses give the fraction of giant-containing systems with another evolved component as $\mathbb E[g^2+2gw]/\mathbb E[2g-g^2]$. Averaging must follow conditioning on age, rather than multiplying marginal state <probabilities>.
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