Amy was the 90th percentile of the 80 grades for her class, therefore, 10% are higher than Amy's, 10%*80 = 8.
19 of the other class was higher than Amy. Totally, 8 + 19 = 27
Then, the percentile is:
(180 - 27)/180 = 85/100
The mind is everything. What you think you become. -Lord Buddha
Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001
www.manyagroup.com