  We construct a family of semi-analytic models for young open clusters,
including a gaseous component and varying assumptions about the distribution
function for the stellar component. The parameters of these models are informed
by observed open clusters and general theoretical considerations regarding
cluster formation. We use this framework to estimate the fraction of the
stellar component that remains gravitationally bound after the gaseous
component disperses. The remaining stellar fraction is a smooth function of the
star formation efficiency, and depends on the distribution function of the
stars. We calculate the fraction of stars remaining for this class of open
cluster models and provide fitting formulae for representative cases.
