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The average number of students per class at School X is 25 and the ave

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The average number of students per class at School X is 25 and the ave  [#permalink]

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New post 10 Jan 2019, 03:06
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The average number of students per class at School X is 25 and the average number of students per class at School Y is 33. Is the average number of students per class for both schools combined less than 29?

1) There are 12 classes in school X.
2) There are more classes in school X than in school Y.

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The average number of students per class at School X is 25 and the ave  [#permalink]

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New post 10 Jan 2019, 05:51
The average number of students per class at School X is 25 and the average number of students per class at School Y is 33. Is the average number of students per class for both schools combined less than 29?

(33+25)/2 = 29
At least equal number of students per class in school x and equal number of students per class in school y should be present for combined average to be 29
OR
Y >x


1) There are 12 classes in school X.
No information about Y
Insufficient

2) There are more classes in school X than in school Y.
From above explanation X > Y, implies avg of students both classes combines is < 29
Sufficient

Option B is correct
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Re: The average number of students per class at School X is 25 and the ave  [#permalink]

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New post 16 Jan 2019, 20:40
Dare Devil wrote:
The average number of students per class at School X is 25 and the average number of students per class at School Y is 33. Is the average number of students per class for both schools combined less than 29?

(33+25)/2 = 29
At least equal number of students per class in school x and equal number of students per class in school y should be present for combined average to be 29
OR
Y >x


1) There are 12 classes in school X.
No information about Y
Insufficient

2) There are more classes in school X than in school Y.
From above explanation X > Y, implies avg of students both classes combines is < 29
Sufficient

Option B is correct


Hi,

Can you please elaborate on the explanation??? I am lost. I did not understand how did you arrive at the conclusion that since x>y the average is <29.
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Re: The average number of students per class at School X is 25 and the ave  [#permalink]

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New post 16 Jan 2019, 22:28
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Kezia9 wrote:
Dare Devil wrote:
The average number of students per class at School X is 25 and the average number of students per class at School Y is 33. Is the average number of students per class for both schools combined less than 29?

(33+25)/2 = 29
At least equal number of students per class in school x and equal number of students per class in school y should be present for combined average to be 29
OR
Y >x


1) There are 12 classes in school X.
No information about Y
Insufficient

2) There are more classes in school X than in school Y.
From above explanation X > Y, implies avg of students both classes combines is < 29
Sufficient

Option B is correct


Hi,

Can you please elaborate on the explanation??? I am lost. I did not understand how did you arrive at the conclusion that since x>y the average is <29.


(33+25)/2 = 29
At least equal number of students per class in school x and equal number of students per class in school y should be present for combined average to be 29
OR
Y >x


you add 25 and 33 can then sum is 29, which is towards 33(more value) in same way (33+25)/2 = 29 if you add more 25's the weightage of the overall average moves towards 25 < 29 (towards the less value)

example:
School X has 3 classes and school Y has 1, then the average will be < 29 (as along as 25's and 33's are equal the average remains at 29, because 33-25 = 8, now we distribute 4 equally i.e., 25+4 = 33-4 but once the Class of X are more than Classes of Y Overall average reduces from 29 moves towards 27

School X has 3 classes and school Y has 1, then the average will be < 29
(25*3+33*1)/29 = 27 < 29

Simple logic is if we have more 25's overall average moves towards it (<29), if more 33 it moves towards it (> 29) from their average (33+25)/2 = 29

Hope it's clear Now
GMAT Club Bot
Re: The average number of students per class at School X is 25 and the ave   [#permalink] 16 Jan 2019, 22:28
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The average number of students per class at School X is 25 and the ave

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