Cambridge Group interview questions

I got a first-round interview but was not able to move forward after that. I applied online both through the Nielsen website and my college's online career search/application system, and also talked with TCG representatives at a college career fair. I believe it was the positive in-person interactions (and email follow-up communications) I had at the career fair that helped me actually get the interview; I don't think my application through Nielsen alone would have gotten a response, because nothing happened for over a month until I got to have more contact with them through my university. My interview was on-campus with 2 different project directors at the firm (each 1:1 interview was 30-45 mins). Unlike most other interviewees that day, I was interviewing for the more specialized Statistical Analyst (SA) position rather than the standard consulting Business Analyst (BA) position. I specifically asked and was told by the hiring manager that unlike the other BA interviews, my interviews would consist only of background/fit questions without a case portion, whereas the BA interviews would include a case portion. So I did not bother to do any case interview prep because I thought there was no reason to expect that type of questions. My first interview matched that expectation and focused on questions about my experience and potential fit with the company and other SA team members. I felt confident walking out of that first interview because I thought it went really well and felt a good connection with the interviewer. Unfortunately, the experience went downhill very quickly when I walked into the second interview and was almost immediately presented with what it took me a few minutes to realize was actually a case problem - this completely threw me for a loop because I'd had zero case problem or consulting-related experience before. I wasn't really doing a consulting job search other than TCG and was mostly interested in the position because of the statistics work, which is my background. That said, I still would have done the relevant preparation or at least tried to familiarize myself with the case interview process if I had not been given the false information that there would be no case problem, which would have at least helped me not get so flustered and have a better idea of how to approach the situation!! So although I wasn't surprised that my poor performance in the case portion prevented me from getting a second-round interview, the experience left a pretty bad taste in my mouth because their interview assessment of me seemed really unfair. I can only assume that either the second interviewer made a mistake and thought I was interviewing for the BA instead of the SA, or he thought it would be a good idea to give me the case problem even when they'd specifically told me not to expect it, as some kind of surprise stress test (how this is helpful to either of us I can't understand, but I guess it was definitely a learning experience for me).