Researchers at a large city hospital are investigating the impact of prenatal care on newborn health. They collected data from 875 births during 2011-2013. They kept track of the mother's age, the number of weeks the pregnancy lasted, the type of birth (natural, C-section), the level of prenatal care the mother received (none, minimal, adequate), the birth weight of the baby, and the sex of the baby.

1. How many cases are involved with this study?
2. Name three quantitative variables in this study and give their units of measure. If the units are not obvious from the description, give your best assumption.
3. Name three qualitative variables in this study AND whether they're ordinal or nominal.