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

Redeem

The ratio of the number of boys to the number of girls in

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 1622
Joined: Thu Mar 01, 2018 7:22 am
Followed by:2 members

The ratio of the number of boys to the number of girls in

by Gmat_mission » Sat Mar 17, 2018 9:19 am
The ratio of the number of boys to the number of girls in a certain school club is 3 to 4. if there are 5 more girls than boys in the club, how many girls are in the club?

A. 7
B. 8
C. 12
D. 15
E. 20

[spoiler]OA=E[/spoiler].

What is the best approach that can be used to solve this PS question? Experts, I'd be thankful for your help.
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 » Sat Mar 17, 2018 5:14 pm
Gmat_mission wrote:The ratio of the number of boys to the number of girls in a certain school club is 3 to 4. if there are 5 more girls than boys in the club, how many girls are in the club?

A. 7
B. 8
C. 12
D. 15
E. 20
One approach:

The ratio of the number of boys to the number of girls in a certain school club is 3 to 4.
So, some possible scenarios are:

3 boys and 4 girls
6 boys and 8 girls
9 boys and 12 girls
.
.
.
There are 5 more girls than boys in the club
So, keep listing scenarios until we have 5 more girls than boys
.
.
12 boys and 16 girls (there are 4 more girls that boys)
15 boys and 20 girls (there are 5 more girls that boys) BINGO!!

Answer: E

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 » Sat Mar 17, 2018 5:16 pm
Gmat_mission wrote:The ratio of the number of boys to the number of girls in a certain school club is 3 to 4. if there are 5 more girls than boys in the club, how many girls are in the club?

A. 7
B. 8
C. 12
D. 15
E. 20
Another approach:

There are 5 more girls than boys in the club
Let G = # of girls in club
So G-5 = # of boys in club

The ratio of the number of boys to the number of girls in a certain school club is 3 to 4.
We can write (G-5)/G = 3/4
Cross multiply: 4(G-5) = 3G
Expand: 4G - 20 = 3G
Solve: G = 20

Answer: E

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] » Sat Mar 17, 2018 7:03 pm
Hi Gmat_mission,

We're told that the ratio of the number of boys to the number of girls in a certain school club is 3 to 4 and that there are 5 more girls than boys in the club. We're asked for the number of girls in the club. This question can be solved in a variety of different ways, including by TESTing THE ANSWERS.

Since the ratio is 3 to 4, the number of boys is a multiple of 3 and the number of girls is an equivalent multiple of 4. Thus, the correct answer must be either B, C or E. In addition, for every 3 boys, there will be one additional girl. With a difference of 5, it's likely that the number of girls is also a multiple of 5. Let's TEST Answer E first.

Answer E: 20 girls
IF there are 20 girls - and 20 = (5)(4)....
there are (5)(3) = 15 boys
20 girls and 15 boys is a difference of 20 - 15 = 5 girls
This is an exact match for what we were told, so this must be the answer.

Final Answer: E

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image
Top
User avatar
GMAT Instructor
Posts: 1462
Joined: Thu Apr 09, 2015 9:34 am
Location: New York, NY
Thanked: 39 times
Followed by:22 members

by Jeff@TargetTestPrep » Wed Mar 21, 2018 3:26 pm
Gmat_mission wrote:The ratio of the number of boys to the number of girls in a certain school club is 3 to 4. if there are 5 more girls than boys in the club, how many girls are in the club?

A. 7
B. 8
C. 12
D. 15
E. 20
We can create the ratio boys : girls = 3x : 4x and create the equation:

3x + 5 = 4x

5 = x

So there are 4 x 5 = 20 girls in the club.

Answer: E

Jeffrey Miller
Head of GMAT Instruction
[email protected]

Image

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews
Top
Legendary Member
Posts: 1622
Joined: Thu Mar 01, 2018 7:22 am
Followed by:2 members

by Gmat_mission » Sat Mar 24, 2018 4:38 am
Thank you all for your help.
Top
Post new topic Post Reply
• Page 1 of 1