When the pressure around the chest wall returns to that of the surrounding air, expiration occurs passively owing to the elastic recoil of the lungs and chest wall. However, during the poliomyelitis epidemic mortality decreased from 87% to 40% when INPV was replaced by positive-pressure ventilation.
Part-Time Per-Credit Costs. The per-credit-hour charge for part-time undergraduate students at Wilmington University in 2015 - 2016 was $346. Typically, college classes consist of 3 or 4 credits, bringing the cost per class to $1,038 or $1,384. At many colleges, full-time tuition kicks in at around 12 credit hours.
How much is it? Community college can cost as little as $20 per credit hour or as much as $200 per credit hour. Since most classes are three credits, and most colleges consider 15 credits full time, this results in a per-semester price of about $300-$3000. This translates to a cost of $600-$6000 per year if attending both fall and winter semesters full time.