UNDATED (CNN) -- How much you pay for college could depend on your major and how close you are to finishing.
A new Cornell University study says more than 140 public universities charge different tuition, depending on major and/or class.
Researchers say it makes sense to charge more for majors that cost more to teach, and/or lead to higher-paying jobs.
That could explain why engineering, business and nursing majors have to pay differential tuition most often.
A recent Georgetown University study showed that engineering majors tend to earn the most. On the other hand, social sciences tend to pay the least.
The Cornell study says economists justify higher tuition for upperclassmen, because those students generally have smaller classes.
And, they're more likely to complete their degrees and reap the economic benefits.