There is no state exam in Michigan. Your class may have a 80% minimum, but there is no state test.
Once you take your class, and pass the "CLASS TEST", and your "CLASS PRACTICAL", then you are elligble to apply for the NREMT written test. Once they verify your practical skills and class finished, you can take the NREMT. % wise for the NR? I really don't know and don't think you should care about it. Just do your best.
Once you pass the NR (or if you do), then you go to the state website located here and fill out the license application packet. Few weeks later you get mailed a small little card, and license certificate thingy. Then you can apply to ambulance companies.