Angela’s grade was in the 90th percentile out of 80 grades in her class. In another class of 100 students there were 19 grades higher than Angela’s. If nobody had Angela’s grade, then Angela was what percentile of the two classes combined?  Pick one:
A) 72
B) 80
C) 81
D) 85
E) 92
If someone's grade is in xth percentile of the nn grades, this means that xx of people out of nn has the grades less than this person.   Being in 90th percentile out of 80 grades means Angela outscored 80∗0.9=7280∗0.9=72 classmates.   In another class she would outscored 100−19=8 students (note: Angela herself is not in this class).   So, in combined classes she outscored   72+81= 
<gadget id="calculator">  72+81</gadget>
<output>153</output>
153. As there are total of   80+100= 
<gadget id="calculator">  80+100</gadget>
<output>180</output>
180 students, so Angela is in   153/180= 
<gadget id="calculator">  153/180</gadget>
<output>17/20 = around 0.85</output>
0.85=85, or in 85th percentile.   Answer: 85.
<result>D</result>
Angela’s grade was in the 90th percentile out of 80 grades in her class. In another class of 100 students there were 19 grades higher than Angela’s. If nobody had Angela’s grade, then Angela was what percentile of the two classes combined?