Suppose 1000 people were forced underground into a relatively well set up bunker style community. Assuming they have no official leadership or organization to begin with, they must rapidly learn their new surroundings, adopt some form of government, and organize to survive. They are all survivors of excessive violence, poverty, and illness and have developed the ability to adapt as a result.
The group is not prepared and may be lacking some skill sets needed for comforts. They are provided with the basics. They have enough nonperishable meals to last until they can get hydroponic gardens setup (which they are equipped for). They have a geothermal energy source and a water source. They are equipped for very basic waste management and recycling, as well as a ventillation system. There are resources to teach them the basics in cases where the appropriate skills are lacking (I’m still building characters). The people who put them here have given them just enough for basic survival. They are on their own beyond that.
Bearing in mind that disturbed circadian rhythms and a lack of sunlight are fairly difficult for adaptation, how many of the thousand (approximately) are unlike to “make it” in that first generation?