Have they said they are taking 250 pre admit? Last year only 181 enrolled pre admit. That is why they took 473 in regular.
473/1284= 36.8%
This is what you are missing: Not all of those 350 preadmits enroll. Believe it or not, Michigan is not the first choice for everyone. Maybe some got into Wharton, Maybe some decided to eschew business. Maybe some got into Princeton and decided to major in classics and then get an MBA.
Maybe some got a free ride to Alabama and went there instead.
Also - Even after enrolling and taking their 1st year at Michigan, some of the preadmits choose not to enroll in Ross or don’t acheive the requisite freshman GPA; and not all accepted as a Soph enrollee choose to enroll in Ross.
Roughly 1/6 to 1/7 of the pre-admits fail to make the GPA cut off. Others choose not to enroll in the school, and others still decide not to continue with the program. My class had accepted 300 Pre-admits, and 181 ended up going to Michigan. I’m assuming 150 of us will actually go on to Ross, leaving 450 spots for RD applicants