我都没读懂题，牛牛们帮帮忙吧~

fankser

Amy's grade was the 90th percentile of the 80 grades for her class. of the 100 grades from another class, 19 were higher than Amy's, the rest were lower than Amy's. if on other grade was the same as Amy's grade, then Amy's grade was what percentile of the grades of the two classes combined?

vevelay

maybe it should be if "no" other grades?

phdmass

同问  if on other grade was the same as Amy's grade，这句话怎么理解？？谢谢

GlendaKuo

Amy班共80人（80份成绩），她的成绩处于90th percentile，也就是说有72个人比她考得没她好，另外一个班级有100人（100份成绩），要是拿Amy的成绩跟另外那个班级的100成绩比，19个人比她考得好，其余81个不如她，问要是两个班级的成绩合在一起，Amy的成绩还能排到X percentile?

解题：两个班级180份成绩，7+19=26人比Amy高，153人不如她，所以答案应该是85th percentile。