GMAT Question of the Day - Daily to your Mailbox; hard ones only
close

It is currently 14 Oct 2019, 06:25
Register
GMAT Club Tests
Decision Tracker
My Rewards
New comers' posts
New posts
Unanswered

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Go to My Error Log Learn more
Close

Request Expert Reply

Confirm Cancel
CLICK HERE TO HIDE/SHOW EVENTS

Some boys and girls are having a car wash to raise money for a class

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
  Sort by Date Sort by Kudos  
Search for:
 
Print view
First unread post
Author Message
TAGS:

Hide Tags

Find Similar Topics 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58311
CAT Tests
Top Member of the Month
Some boys and girls are having a car wash to raise money for a class  [#permalink]

Show Tags

New post 26 Mar 2019, 23:16
2
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

83% (02:04) correct 17% (02:43) wrong based on 42 sessions

HideShow timer Statistics

Some boys and girls are having a car wash to raise money for a class trip to China. Initially 40% of the group are girls. Shortly thereafter two girls leave and two boys arrive, and then 30% of the group are girls. How many girls were initially in the group?

(A) 4
(B) 6
(C) 8
(D) 10
(E) 12
Spoiler: OA

_________________
New to the GMAT CLUB Forum?
Posting Rules: QUANTITATIVE | VERBAL. Guides and Resources: QUANTITATIVE | VERBAL | Ultimate GMAT Quantitative Megathread | All You Need for Quant

Questions' Banks and Collection:
PS: Standard deviation | Tough Problem Solving Questions With Solutions | Probability and Combinations Questions With Solutions | Tough and tricky exponents and roots questions | 12 Easy Pieces (or not?) | Bakers' Dozen | Algebra set | Mixed Questions | Fresh Meat
DS: DS Standard deviation | Inequalities | 700+ GMAT Data Sufficiency Questions With Explanations | Tough and tricky exponents and roots questions | The Discreet Charm of the DS | Devil's Dozen!!! | Number Properties set | New DS set
MIXED: GMAT Club's Complete Questions' Bank | SEVEN SAMURAI OF 2012 | Tricky questions from previous years. | Special Questions' Directory | Best Of The Best Of 2017 | The Best Of Quant of 2016 | 20 hardest and 20 best questions of 2015 | 15 best topics of 2015 | Seven Samurai of 2012 | GMAT Probability Questions

What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics
Signature Read More
Intern
Intern
avatar
B
Joined: 27 Sep 2018
Posts: 37
Re: Some boys and girls are having a car wash to raise money for a class  [#permalink]

Show Tags

New post 26 Mar 2019, 23:50
1
Let total number of children in group be x
Number of girls=0.4x
No. Of girls after 2 girls left
0.4x-2=0.3x
X=20
No. Of girls initially in the group=0.4x=8

Posted from my mobile device
GMAT Club Legend
GMAT Club Legend
User avatar
D
Joined: 18 Aug 2017
Posts: 4978
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
GMAT ToolKit User Premium Member
Re: Some boys and girls are having a car wash to raise money for a class  [#permalink]

Show Tags

New post 27 Mar 2019, 01:32
Bunuel wrote:
Some boys and girls are having a car wash to raise money for a class trip to China. Initially 40% of the group are girls. Shortly thereafter two girls leave and two boys arrive, and then 30% of the group are girls. How many girls were initially in the group?

(A) 4
(B) 6
(C) 8
(D) 10
(E) 12


b+g=x
so
0.4x=girls
0.4x-2=0.3x
solve x= 20
so 0.4*20 ; 8
ImO C
_________________
If you liked my solution then please give Kudos. Kudos encourage active discussions.
Signature Read More
Intern
Intern
avatar
Joined: 25 Mar 2019
Posts: 1
Re: Some boys and girls are having a car wash to raise money for a class  [#permalink]

Show Tags

New post 28 Mar 2019, 10:17
1
We know the Total is sum of boys and girls. However, since 40% are girls - we have a ratio given of boys to girls = 60 : 40 = 6 : 4
(for ease of calculation, I would not simplify the ratio to 3:2) --->
Number of boys = 6X
Number of girls = 4X

It is important to use X because while 6:4 is a ratio, 6X and 4X are absolute values that we do not know yet.

Two girls leave, so number of girls (new) = 4X - 2
Two boys added, so number of boys (new) = 6X + 2

The ratio between these two new values = (4X-2)/(6X+2) ---> which is given to be equal to 30/70.
Solve (4X-2)/(6X+2) = 3/7
and we get X = 2.
Thus, number of girls initially = 4X = 8
Ans: C
Target Test Prep Representative
User avatar
D
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8040
Location: United States (CA)
Re: Some boys and girls are having a car wash to raise money for a class  [#permalink]

Show Tags

New post 31 Mar 2019, 11:50
Bunuel wrote:
Some boys and girls are having a car wash to raise money for a class trip to China. Initially 40% of the group are girls. Shortly thereafter two girls leave and two boys arrive, and then 30% of the group are girls. How many girls were initially in the group?

(A) 4
(B) 6
(C) 8
(D) 10
(E) 12


We can let the original number of girls = 0.4n and the original number of boys = 0.6n.

Since two girls leave and two boys arrive, leaving 30% of the group as girls, we have:

(0.4n - 2)/(n - 2 + 2) = 3/10

(0.4n - 2)/n = 3/10

10(0.4n - 2) = 3n

4n - 20 = 3n

n = 20

Therefore, there were 0.4 x 20 = 8 girls originally.

Answer: C
_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Signature Read More
GMAT Club Bot
Re: Some boys and girls are having a car wash to raise money for a class   [#permalink] 31 Mar 2019, 11:50
Print view
First unread post
Display posts from previous: Sort by

Some boys and girls are having a car wash to raise money for a class

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  

Moderators: chetan2u, Bunuel, VeritasKarishma, Gladiator59, generis

Search for:





Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Main navigation

GMAT Resources

Partners

MBA Resources

www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions