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Amy's grade was the 90th percentile of the 80 grades for her [#permalink]
22 Sep 2005, 20:53
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Amy's grade was the 90th percentile of the 80 grades for her class. Of the 100 grades for another class, 19 were higher than Amy's, and the rest were lower. If no other grade was the same as Amy's grade, then Amy's grade was what percentile of the grades of the two classes combined?
Amy = 90th percentile which means she was ranked above 72=73 as nobody got the same grade as Amy. Thus, 7 people got higher than her in the 80. From the second class 19 people got higher than her, making it a grand total of 26 people with higher grades than her. Leaving 153 people below her score.
153*100/180 gives the percentile score = 85th percentile.
Mistakenly, I calculated that there were 154 people below her because I did not take into account that fact that no two people got the same grade but I still ended up with ~85.5 which was the closest answer.