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GRE Prep Club Team Member
Joined: 20 Feb 2017
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Amy's grade was 90th percentile of the 80 grades for her class. Of the
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24 Sep 2022, 06:54
24 Sep 2022, 06:54
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Amy's grade was 90th percentile of the 80 grades for her class. Of the 100 grades from 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 of two classes combined?
A. 72nd
B. 80th
C. 81st
D. 85th
E. 92nd
A. 72nd
B. 80th
C. 81st
D. 85th
E. 92nd
Re: Amy's grade was 90th percentile of the 80 grades for her class. Of the
[#permalink]
28 Sep 2022, 09:29
28 Sep 2022, 09:29
Expert Reply
If someone's grade is in \(x_{th}\) percentile of the \(n\) grades, this means that \(x%\) of people out of \(n\) has the grades less than this person.
Being in 90th percentile out of 80 grades means Amy outscored \(80*0.9=72\) classmates.
In another class she would outscored \(100-19=81\) students (note: Amy herself is not in this class).
So, in combined classes she outscored \(72+81=153\). As there are total of \(80+100=180\) students, so Amy is in \(\frac{153}{180}=0.85=85%\), or in 85th percentile.
Answer: D.
Being in 90th percentile out of 80 grades means Amy outscored \(80*0.9=72\) classmates.
In another class she would outscored \(100-19=81\) students (note: Amy herself is not in this class).
So, in combined classes she outscored \(72+81=153\). As there are total of \(80+100=180\) students, so Amy is in \(\frac{153}{180}=0.85=85%\), or in 85th percentile.
Answer: D.
gmatclubot
Re: Amy's grade was 90th percentile of the 80 grades for her class. Of the [#permalink]
28 Sep 2022, 09:29
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