How likely are you to be accepted into one undergaduate medicine course in australia with a 90 percentile umat and 99.0 atar?
If so which one/s?
You'll get into UQ, no questions asked, although the UMAT has slightly been creeping up, so you might even struggle with the 90th.
My gut feeling is that with a 90th Percentile, you'll struggle with Monash, even though you'll get a late interview, because look at it this way
There's a lot of people who have gotten 90-100th Percentile and have gotten 99.00+ ATARs as well, you'll have to beat them in the interview by enough of a margin to win back your loss in the UMAT.
You really really need to get 95th+ in UMAT to really be competitive for Medicine at Monash, just because of the sheer number of people with good ATARs and UMATs.