This is the most subjective standardized test I've ever encountered or heard of. No one really knows. It seems to vary with every reporting period. Sometimes people pass with 6 x's in the lower performance category, other times I've seen someone fail with 3 x's.
Study First Aid, go in to every encounter with a plan, write the note like you've practiced. US students have a 95%+ pass rate, IMGs are still in 70s/80s