Answer:
Army's grade was 85 percentile of grades of two class combined.
Step-by-step explanation:
Consider the provided information.
It is given that Amy's grade was the 90th percentile of the 80 grades for her class.
The means the number of classmate is: [tex]80\times0.9=72[/tex].
Of the 100 grades from another class, 19 was higher than Amy's and the rest was lower.
100−19=81 students
So, in combined classes she outscored 72+81=153
The total number of students are 80+100= 180
[tex]\frac{153}{180}=0.85[/tex]
Hence, Army's grade was 85 percentile of grades of two class combined.