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 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 combined?
A. 72nd
B. 80th
C. 81st
D. 85th
E. 92nd
Please Help....
Thanks.
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Gmat Prep?? (Amy's Grade)
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sudhir3127
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I go with D 85thdferm wrote: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 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 combined?
A. 72nd
B. 80th
C. 81st
D. 85th
E. 92nd
Please Help....
Thanks.
90% percentile out of 80 means 8 students were above her.
out of another 100 students 19 were above her.
total number of students above her out of 180 students are 27.
thus Amy grade was 153/180 = 85th percentile.
Hope that helps...
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arora007
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Joe bloggs did not work here... 
my guess was 80th was out.. and also 85th out because of the below explanation...
B. 80th
C. 81st
D. 85th
90th percentile of 80 and standing at around 80th percentile of 100, I assumed that the answer should have been more closer to 80th percentile as 100 weighs more... but the critical mistake I did was taking 19 ahead than me as 80th percentile. The keyword "from the other class" failed to strike me!! Had I taken it 81st percentile, I might have tried the
weighted average formula.
aneways...Let bygones are bygones!
my guess was 80th was out.. and also 85th out because of the below explanation...
B. 80th
C. 81st
D. 85th
90th percentile of 80 and standing at around 80th percentile of 100, I assumed that the answer should have been more closer to 80th percentile as 100 weighs more... but the critical mistake I did was taking 19 ahead than me as 80th percentile. The keyword "from the other class" failed to strike me!! Had I taken it 81st percentile, I might have tried the
weighted average formula.
aneways...Let bygones are bygones!
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sudhir3127 wrote:I got D as well. The way I figured it out was 80*0.9= 72, so this means that in the first class there were 8 people ahead of her. Add this to the 19 in the other class you get 27. So there were 27 out of 180 people ahead of her. I did some fancy quick arithmatic to figure out that it is 13.5 out of 90, 135 out of 900, 135/9 is 15. 100-15=85!dferm wrote: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 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 combined?
A. 72nd
B. 80th
C. 81st
D. 85th
E. 92nd
Please Help....
Thanks.
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bblast
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i solved this by weigted average and got the correct answer, but I guess the aproachh should have been the percntile one ?arora007 wrote:Joe bloggs did not work here...
my guess was 80th was out.. and also 85th out because of the below explanation...
B. 80th
C. 81st
D. 85th
90th percentile of 80 and standing at around 80th percentile of 100, I assumed that the answer should have been more closer to 80th percentile as 100 weighs more... but the critical mistake I did was taking 19 ahead than me as 80th percentile. The keyword "from the other class" failed to strike me!! Had I taken it 81st percentile, I might have tried the
weighted average formula.
aneways...Let bygones are bygones!
Cheers !!
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Verbal 34-Striving for 40
My gmat journey :
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My take on the GMAT RC :
https://www.beatthegmat.com/ways-to-bbla ... 90808.html
How to prepare before your MBA:
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GMATGuruNY
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Percentile means the percentage below.dferm wrote: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 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 combined?
A. 72nd
B. 80th
C. 81st
D. 85th
E. 92nd
Please Help....
Thanks.
Out of 80 grades, if Amy's grade was the 90th percentile, then 90% of the grades were lower than Linda's grade. Thus, .9*80 = 72 grades in Amy's class were lower than Amy's grade. Subtracting these 72 grades and Amy's grade from the total, we get that 80-72-1 = 7 grades were higher.
Since 19 grades in the other class were higher than Amy's grade, 19+7 = 26 grades in the combined classes were higher than Amy's grade. Subtracting these 26 grades and Amy's grade from the total number of grades in the combined classes, we get that 180-26-1 = 153 grades were lower than Amy's grade.
Thus, Amy's percentile in the combined classes was 153/180*100 = 85%.
The correct answer is D.
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Anaira Mitch
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Being in 90th percentile out of 80 grades means Amy outscored 80∗0.9=7280∗0.9=72 classmates.
In another class she would outscored 100−19=81100−19=81 students (note: Amy herself is not in this class).
So, in combined classes she outscored 72+81=15372+81=153. As there are total of 80+100=18080+100=180 students, so Amy is in 153180=0.85=85153180=0.85=85, or in 85th percentile.
Answer: D.
In another class she would outscored 100−19=81100−19=81 students (note: Amy herself is not in this class).
So, in combined classes she outscored 72+81=15372+81=153. As there are total of 80+100=18080+100=180 students, so Amy is in 153180=0.85=85153180=0.85=85, or in 85th percentile.
Answer: D.
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Jeff@TargetTestPrep
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Since Amy's grade is in the 90th percentile of the 80 grades in her class, 10% of the number of total grades in her class are not lower than Amy's grade; i.e., 8 grades. Note that these 8 grades include Amy's own grade. When combined with the number of grades from the other class, there are 8 + 19 = 27 grades that are not lower than Amy's grade, including Amy's own, in a total of 80 + 100 = 180 grades. Since 27 / 180 = 0.15, this amounts to 15% of all the grades. Therefore, Amy's grade is the 100 - 15 = 85th percentile of the combined grades of the two classes.dferm wrote: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 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 combined?
A. 72nd
B. 80th
C. 81st
D. 85th
E. 92nd
Answer: D
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