What are my chances of getting into the University of Michigan?

The required GPA is a 3.5 so you're fine in that area. The extra curriculars seem to be alright, the issue may be the ACT score. I don't think any college will pick the best individual scores, I think they just take the best overall ACT you have. And while a 24 is a good score for the ACT, I believe UofM requires something like a 27 or 28 for admittance. However, that does not automatically rule you out, but it seems that will be your biggest deterrent.