BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Ratio

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Master | Next Rank: 500 Posts
Posts: 154
Joined: Wed May 21, 2014 4:29 am
Thanked: 8 times
Followed by:1 members

Ratio

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?
Top
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

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

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

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

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top

GMAT/MBA Expert

User avatar
Elite Legendary Member
Posts: 10392
Joined: Sun Jun 23, 2013 6:38 pm
Location: Palo Alto, CA
Thanked: 2867 times
Followed by:511 members
GMAT Score:800

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?

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 154
Joined: Wed May 21, 2014 4:29 am
Thanked: 8 times
Followed by:1 members

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,
Rich
Hi, it's from GRE resource.
Top

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

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.

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Post new topic Post Reply
• Page 1 of 1