Same school or not, these are hardly typical figures for Michigan high schools. The University of Michigan admits applicants from Ann Arbor-area schools at extremely high rates. In part it’s because they tend to be among the better schools in the state. In part, it may be because many applicants from these schools enjoy a legacy advantage; the density of Michigan alums is probably higher in and around Ann Arbor than anywhere else in the state, and so is the density of alumni offspring, and Michigan does give a definite admissions bump to legacies. In part in may be an admissions preference for the children of university faculty and staff; this doesn’t show up in, e.g., the Common Data Set, but it’s a practice widely followed by most public and private universities. In any event, having half the class apply, and half of those who apply be admitted, is pretty much off the charts. I’d be surprised if as many as 6 or 8 schools in the state can claim numbers like that.