Dennis Group interview questions

First round "Interview" was a discussion at a college career fair; I was told I would be contacted if there was an opening I was qualified for. Several weeks later, I was emailed and offered an interview. The second round interview was 8 hours. The first two of which were case study.

Got an email asking me to come in for an interview at their office about two months after giving them my resume at a career fair. During the interview, I met with several mechanical engineers (at once, conference style) and later with an HR person. The HR person essentially explained everything about the company, benefits, work style etc., and asked general interview questions and went over my resume. With the mechanical engineers, it felt like they were just trying to know me and asked me a few points on my resume and no technical questions. They explained what their jobs entailed and were basically trying to see if I would be a good fit within the department. I got an email about 3 weeks later saying I was rejected.