Case Study Rejected

I got an interview with a recruiter who was impressed with me, then I got an interview with the hiring manager who was also impressed, then I was told to do a case study. I analyzed the data (which wa

I got an interview with a recruiter who was impressed with me, then I got an interview with the hiring manager who was also impressed, then I was told to do a case study. I analyzed the data (which was in excel) and created beautiful slides with all the information needed but the hiring manager who interviewed me decided to not move me forward to the final interviews after reviewing it. I am confused as to why and if I should even asked for feedback. This was a whole week of work and completely unpaid. I fit the role completely to the point where even the recruiter was shocked at my relevant experience. I am pretty upset because I made sure everything was accurate. The only thing was that I rounded the number of percentages (instead of it being 51.96 % I put 52%) so I don’t think that should even be an issue? Also why do they even do assessments, like the data is not enough to even come up with solid analysis. Edit: I understand now that I was used for free work. The red flag was that they said the data was not structured and there wasn’t really any data analytics person there so they used me to do their analysis since I had those skills on top of the skills in my current role. This sucks 😞