Extinction probability of a linear birth-death process
= Extinction probability of a linear birth-death process
For individual birth and death rates $\lambda,\mu$ and one initial individual, the finite-time extinction probability satisfies
$$
h'=(h-1)(\lambda h-\mu),\qquad h(0)=0.
$$
When $\lambda\ne\mu$,
$$
h(t)=\frac{\mu(1-e^{-(\lambda-\mu)t})}
{\lambda-\mu e^{-(\lambda-\mu)t}}.
$$