Part-time but given 40 hours a week?

Hey all,

I just got off the phone with the Fedex recruiter. I applied for a part-time warehouse position and they said my shifts are from 3p-11p. I was under the assumption that shifts for part-time were around 5 hours. I'm starting business school in two weeks and while I understand that the managers probably don't give a shit, it's my number one priority. I have no issue with the work, but I just want to be clear on what my hours will be. Are the hours negotiable or not?