I'm in the MMHS, according to our journal (which corresponds directly with OMSAS) from the last year (2010-2011), Western's grading system is equivalent to Mac. 90-100 is a 4.0, 85-89 is a 3.9 and 80-84 is a 3.7.
As for AMCAS, they are slightly more lenient in the sense that 11's, which are graded as 3.9's here, are considered 4.0's during GPA calculation.
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