What are my chances of getting into medical school with one W?

At typical quarter system schools, 15-16 credits per quarter are needed to graduate in 12 quarters or 4 academic years, requiring 180-192 credits. The minimum to be full time for financial aid purposes is 12 credits. However, a credit on the quarter system is equal to 2/3 of a credit on the semester system, because a quarter is 2/3 as long as a semester.