GMAT Prep - Amy's Grade

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GMAT Prep - Amy's Grade

by tutonaranjo » Mon Sep 03, 2007 5:46 pm
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 classes combined.
a) 72nd
b) 80th
c) 81st
d) 85th
e) 92nd

Answer is D
No idea what this means or how to set it up. Supposedly easy.
Appreciate a detailed explanation.
Source: — Problem Solving |

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Re: GMAT Prep - Amy's Grade

by jaspreet.sharma » Mon Sep 03, 2007 10:14 pm
tutonaranjo 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 classes combined.
a) 72nd
b) 80th
c) 81st
d) 85th
e) 92nd

Answer is D
No idea what this means or how to set it up. Supposedly easy.
Appreciate a detailed explanation.
Amy's grade was the 90th percentile means people above Amy are 10
from another class, 19 were higher than Amy's, This means total 10 + 19 people are above AMy

This means 100- (29/ 180 ) is the new percentile of Amy = approx 85

So answer is D

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Re: GMAT Prep - Amy's Grade

by hopefully » Wed Sep 05, 2007 2:58 am
jaspreet.sharma wrote:
tutonaranjo 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 classes combined.
a) 72nd
b) 80th
c) 81st
d) 85th
e) 92nd

Answer is D
No idea what this means or how to set it up. Supposedly easy.
Appreciate a detailed explanation.
Amy's grade was the 90th percentile means people above Amy are 10
from another class, 19 were higher than Amy's, This means total 10 + 19 people are above AMy

This means 100- (29/ 180 ) is the new percentile of Amy = approx 85

So answer is D
Jaspreet,

In class of 80 90 percentile means 8 ( and not 10 ) are above AMY..
final percentile is

1- 27/180 which is exactly = 85..

hope that helps when u hv close choices..


For the rest - X percentile of AMY means X % of the total students scored less than AMY

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by samirpandeyit62 » Sat Sep 08, 2007 11:29 pm
I agree with Hopefully's solution, IMO this one should be used and ans would be D, however please dont try to find percentiles in individual classes and then take their averages as the classes have different strenghts.
Regards
Samir