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by talaangoshtari » Tue May 12, 2015 8:17 am
In a class of 60 boys and girls, $240 was divided in such a way that each girl gets $5 and each boy $3. Find the number of girls in class.

A.30
B.35
C.40
D.48

How can we solve this problem by using alligation approach?
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by Brent@GMATPrepNow » Tue May 12, 2015 8:55 am
talaangoshtari wrote:In a class of 60 boys and girls, $240 was divided in such a way that each girl gets $5 and each boy $3. Find the number of girls in class.

A.30
B.35
C.40
D.48
$240 was divided among 60 students.
This means that the average amount that each student received = $240/60 = $4

Since $4 is EXACTLY in the middle of $3 and $5, we can conclude that the number of boys = the number of girls.
So, there must be 30 boys and 30 girls.

Answer: A

This concept is covered in our free video: https://www.gmatprepnow.com/module/gmat- ... ics?id=805

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by Brent@GMATPrepNow » Tue May 12, 2015 8:59 am
talaangoshtari wrote:In a class of 60 boys and girls, $240 was divided in such a way that each girl gets $5 and each boy $3. Find the number of girls in class.

A.30
B.35
C.40
D.48
Another approach is to use algebra.

Let B = # boys
Let G = # girls

In a class of 60 boys and girls....
So, we can write: B + G = 60

$240 was divided in such a way that each girl gets $5 and each boy $3
So, we can write: 3B + 5G = 240

We now have a system of two equations with two variables.
B + G = 60
3B + 5G = 240

If we solve this system (which I'll let others do), we get [spoiler]B = 30 and G = 30[/spoiler]

Answer: A

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by [email protected] » Tue May 12, 2015 9:04 am
Hi talaangoshtari,

What is the source of this question? Is it from a GMAT resource or from something else?

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by talaangoshtari » Tue May 12, 2015 9:07 am
[email protected] wrote:Hi talaangoshtari,

What is the source of this question? Is it from a GMAT resource or from something else?

GMAT assassins aren't born, they're made,
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Hi, it's from GRE resource.
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by Brent@GMATPrepNow » Tue May 12, 2015 9:08 am
Rich is asking because there are only 4 answer choices.
GMAT questions have 5 answer choices.
Even GRE questions of this nature have 5 answer choices.

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