Last visit was: 25 Apr 2026, 00:33 It is currently 25 Apr 2026, 00:33
Home
Messages
Tests
Schools
Events
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
Back to Forum
Create Topic
User avatar
enigma123
User avatar
Joined: 25 Jun 2011
Last visit: 16 Mar 2016
Posts: 392
Own Kudos:
19,863
 [7]
Given Kudos: 217
Status:Finally Done. Admitted in Kellogg for 2015 intake
Location: United Kingdom
Concentration: International Business, Strategy
GMAT 1: 730 Q49 V45
GPA: 2.9
WE:Information Technology (Consulting)
GMAT 1: 730 Q49 V45
Posts: 392
Kudos: 19,863
 [7]
The contents of a bag of marbles consist of 9 green marbles Updated on: 16 Mar 2012, 04:35
Originally posted by enigma123 on 16 Mar 2012, 04:24.
Last edited by Bunuel on 16 Mar 2012, 04:35, edited 1 time in total.
Edited the OA
Kudos
Add Kudos
7
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

25% (medium)

Question Stats:

76% (01:31) correct 24% (01:48) wrong based on 407 sessions

History

Date
Time
Result
Not Attempted Yet
The contents of a bag of marbles consist of 9 green marbles and 16 blue marbles. How many blue marbles must be removed so that 60% of the marbles in the bag will be green?

(A) 1
(B) 6
(C) 7
(D) 9
(E) 10

Relatively easy question and I think I have a problem with the concept. Can someone please explain?
ShowHide Answer
Official Answer
E
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 25 Apr 2026
Posts: 109,821
Own Kudos:
811,107
Given Kudos: 105,876
Products:
GMAT Club Tests Forum Quiz
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,821
Kudos: 811,107
The contents of a bag of marbles consist of 9 green marbles 16 Mar 2012, 04:34
Kudos
Add Kudos
Bookmarks
Bookmark this Post
enigma123
The contents of a bag of marbles consist of 9 green marbles and 16 blue marbles. How many blue marbles must be removed so that 60% of the marbles in the bag will be green?

(A) 1
(B) 6
(C) 7
(D) 9
(E) 10

Relatively easy question and I think I have a problem with the concept. Can someone please explain?
Show more

Say we remove x blue marbles, so there will be 9+16-x marbles in the bag. We want 9 green marbles to compose 60% of this number: 0.6(9+16-x)=9 --> x=10.

Answer: E.
User avatar
msvel2304
User avatar
Joined: 21 Sep 2011
Last visit: 12 Oct 2014
Posts: 90
Own Kudos:
28
 [1]
Given Kudos: 18
Concentration: Entrepreneurship, General Management
Schools: Babson '15 (WL) Kelley '15 (D) Carlson '15 (A) Rotman '15 (A) ISB '14 (D) Wake Forest '15 (WL)
GMAT 1: 530 Q42 V20
GMAT 2: 540 Q43 V28
GMAT 3: 680 Q48 V35
WE:Business Development (Hospitality and Tourism)
Schools: Babson '15 (WL) Kelley '15 (D) Carlson '15 (A) Rotman '15 (A) ISB '14 (D) Wake Forest '15 (WL)
GMAT 3: 680 Q48 V35
Posts: 90
Kudos: 28
 [1]
The contents of a bag of marbles consist of 9 green marbles 16 Mar 2012, 07:13
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
We have 9 green and 16 blue marbles.

60% = 9 green marbles
rest 40% = 6, which needs to blue marbles.

6 should be in the bag, so we need to remove 10 marbles.

IMO E.
User avatar
Carcass
User avatar
Board of Directors
Joined: 01 Sep 2010
Last visit: 23 Apr 2026
Posts: 4,709
Own Kudos:
37,847
 [1]
Given Kudos: 4,925
Posts: 4,709
Kudos: 37,847
 [1]
The contents of a bag of marbles consist of 9 green marbles 02 Jun 2012, 04:00
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
A bit of logic.

9G + 16B = 25

60% of 25 = 15

To have our 15 we have to cut the B and to have 6 to obtain 15. The difference is 10. E is the answer
avatar
Pedigo12
avatar
Joined: 06 Aug 2012
Last visit: 08 Mar 2014
Posts: 1
Own Kudos:
1
 [1]
Given Kudos: 6
Posts: 1
Kudos: 1
 [1]
The contents of a bag of marbles consist of 9 green marbles 21 Aug 2012, 11:14
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I just set it up like this.

9/X marbles = .60 ==> solve for x equals 15 marbles. 25-10 = 15.
User avatar
kanusha
User avatar
Joined: 25 Mar 2013
Last visit: 03 Aug 2017
Posts: 156
Own Kudos:
158
Given Kudos: 101
Location: United States
Concentration: Entrepreneurship, Marketing
Schools: Yale '17 HBS '17 Stanford '17
GPA: 3.5
Products:
My Reviews
Schools: Yale '17 HBS '17 Stanford '17
Posts: 156
Kudos: 158
The contents of a bag of marbles consist of 9 green marbles 22 Sep 2013, 20:38
Kudos
Add Kudos
Bookmarks
Bookmark this Post
9 green, 16 blue = 25 marbles
60% = 9 marbles , 100% = 15 marbles
so in 15 9 green and 10 blue
avatar
kalrac
avatar
Joined: 09 Mar 2010
Last visit: 20 Jul 2014
Posts: 14
Own Kudos:
92
Given Kudos: 17
Concentration: Technology, General Management
Schools: McCombs '14
Schools: McCombs '14
Posts: 14
Kudos: 92
The contents of a bag of marbles consist of 9 green marbles 23 Sep 2013, 07:40
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I Just did it this way,
Since the bag should contain 60% green marbles and rest Blue Marbles,

x/(9+16) = 60% ==> x= 15 ==> 9+ 6 , so 10 blue marbles will be removed.
User avatar
EMPOWERgmatRichC
User avatar
Major Poster
Joined: 19 Dec 2014
Last visit: 31 Dec 2023
Posts: 21,777
Own Kudos:
13,047
Given Kudos: 450
Status:GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Expert
Expert reply
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Posts: 21,777
Kudos: 13,047
The contents of a bag of marbles consist of 9 green marbles 21 Jan 2015, 20:33
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hi All,

This question is rooted in basic arithmetic. Since the question asks how many marbles need to be removed and the answers ARE numbers, we can TEST THE ANSWERS until we find the one that "fits."

To start, we have a bag of marbles....
9 green
16 blue
25 total

We're asked to remove blue marbles until the green marbles make up 60% of the bag....

Right now, green marbles make up 9/25 = 36% of the bag, so we clearly need to remove a bunch of blue marbles to change this percentage. Looking at the answers, I'd TEST one of the larger options first...

Let's TEST D....

IF 9 blue marbles were removed, then we'd have...
9 green
7 blue
16 total
9/16 is NOT 60% exactly, but it's pretty close....

Let's TEST E...

IF 10 blue marbles were removed, then we'd have...
9 green
6 blue
15 total
9/15 IS 60%, so this MUST be the answer!

Final Answer:
Show Spoiler
E

GMAT assassins aren't born, they're made,
Rich
User avatar
EMPOWERgmatRichC
User avatar
Major Poster
Joined: 19 Dec 2014
Last visit: 31 Dec 2023
Posts: 21,777
Own Kudos:
13,047
Given Kudos: 450
Status:GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Expert
Expert reply
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Posts: 21,777
Kudos: 13,047
The contents of a bag of marbles consist of 9 green marbles 21 Jan 2015, 20:33
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hi All,

This question is rooted in basic arithmetic. Since the question asks how many marbles need to be removed and the answers ARE numbers, we can TEST THE ANSWERS until we find the one that "fits."

To start, we have a bag of marbles....
9 green
16 blue
25 total

We're asked to remove blue marbles until the green marbles make up 60% of the bag....

Right now, green marbles make up 9/25 = 36% of the bag, so we clearly need to remove a bunch of blue marbles to change this percentage. Looking at the answers, I'd TEST one of the larger options first...

Let's TEST D....

IF 9 blue marbles were removed, then we'd have...
9 green
7 blue
16 total
9/16 is NOT 60% exactly, but it's pretty close....

Let's TEST E...

IF 10 blue marbles were removed, then we'd have...
9 green
6 blue
15 total
9/15 IS 60%, so this MUST be the answer!

Final Answer:
Show Spoiler
E

GMAT assassins aren't born, they're made,
Rich
User avatar
KSBGC
User avatar
Joined: 31 Oct 2013
Last visit: 10 Mar 2022
Posts: 1,240
Own Kudos:
1,509
Given Kudos: 635
Concentration: Accounting, Finance
GPA: 3.68
WE:Analyst (Accounting)
Posts: 1,240
Kudos: 1,509
The contents of a bag of marbles consist of 9 green marbles 20 Apr 2018, 14:09
Kudos
Add Kudos
Bookmarks
Bookmark this Post
enigma123
The contents of a bag of marbles consist of 9 green marbles and 16 blue marbles. How many blue marbles must be removed so that 60% of the marbles in the bag will be green?

(A) 1
(B) 6
(C) 7
(D) 9
(E) 10

Relatively easy question and I think I have a problem with the concept. Can someone please explain?
Show more


This question is noting but a foul question. Just apply your common sense. Blue marbles are more than green marbles. Now what you want to do. You want to make green marbles 60%. Just think. In order to do it is asked to remove some blue marbles. we don't know how many marbles we remove to meet the condition. if blue and green marbles are equal , i mean, 9/9............it is 50%......green 50% ...........blue is 50%..........therefore all the option A to D is out. Only option E is left.
avatar
Funsho84
avatar
Joined: 08 Sep 2016
Last visit: 13 Aug 2022
Posts: 74
Own Kudos:
69
Given Kudos: 25
Posts: 74
Kudos: 69
The contents of a bag of marbles consist of 9 green marbles 20 Apr 2018, 15:00
Kudos
Add Kudos
Bookmarks
Bookmark this Post
(9/(25-x))*100 = 60
900 = 60*(25-x)
900=1500 -60x
x=10
answer E
User avatar
ScottTargetTestPrep
User avatar
Target Test Prep Representative
Joined: 14 Oct 2015
Last visit: 24 Apr 2026
Posts: 22,286
Own Kudos:
26,534
 [1]
Given Kudos: 302
Status:Founder & CEO
Affiliations: Target Test Prep
Location: United States (CA)
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 22,286
Kudos: 26,534
 [1]
The contents of a bag of marbles consist of 9 green marbles 24 Aug 2019, 05:32
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
enigma123
The contents of a bag of marbles consist of 9 green marbles and 16 blue marbles. How many blue marbles must be removed so that 60% of the marbles in the bag will be green?

(A) 1
(B) 6
(C) 7
(D) 9
(E) 10

Relatively easy question and I think I have a problem with the concept. Can someone please explain?
Show more

If 60% of the marbles in the bag must be green, then 40%, or ⅖, of the marbles will be blue. Letting n = the number of blue marbles to be removed, we can create the equation:

(16 - n)/(25 - n) = 2/5

80 - 5n = 50 - 2n

30 = 3n

10 = n

Alternate Solution:

Notice that, no matter how many blue marbles are removed, there are still 9 green marbles in the bag, and we want this number to be 60% of all the marbles. Thus, after the removal of blue marbles, there should be 9/0.6 = 15 marbles in the bag. Since there were 9 + 16 = 25 marbles in the bag to begin with, 25 - 15 = 10 blue marbles should be removed.

Answer: E
User avatar
BrentGMATPrepNow
User avatar
Major Poster
Joined: 12 Sep 2015
Last visit: 31 Oct 2025
Posts: 6,733
Own Kudos:
36,459
Given Kudos: 799
Location: Canada
Expert
Expert reply
Posts: 6,733
Kudos: 36,459
The contents of a bag of marbles consist of 9 green marbles 24 Aug 2019, 07:17
Kudos
Add Kudos
Bookmarks
Bookmark this Post
enigma123
The contents of a bag of marbles consist of 9 green marbles and 16 blue marbles. How many blue marbles must be removed so that 60% of the marbles in the bag will be green?

(A) 1
(B) 6
(C) 7
(D) 9
(E) 10
Show more

GIVEN: Start with 9 green marbles and 16 blue marbles

Let x = the number of BLUE marbles to remove
So, the NEW number of blue marbles remaining = 16 - x
The number of green marbles remaining = 9

How many blue marbles must be removed so that 60% of the marbles in the bag will be green?
We want: (number of GREEN marbles)/(TOTAL number of marbles) = 60%
Rewrite as: (number of GREEN marbles)/(TOTAL number of marbles) = 3/5

Plug in values to get: (9)/(16 - x + 9) = 3/5
Simplify to get: (9)/(25 - x) = 3/5
Cross multiply to get: (5)(9) = 3(25 - x)
Expand to get: 45 = 75 - 3x
Keep going: -30 = -3x
Solve: x = 10

Answer: E

Cheers,
Brent
User avatar
Mohammadmo
User avatar
Joined: 29 Jun 2019
Last visit: 03 Nov 2022
Posts: 346
Own Kudos:
250
Given Kudos: 16
Posts: 346
Kudos: 250
The contents of a bag of marbles consist of 9 green marbles 24 Aug 2019, 09:44
Kudos
Add Kudos
Bookmarks
Bookmark this Post
GMATPrepNow
enigma123
The contents of a bag of marbles consist of 9 green marbles and 16 blue marbles. How many blue marbles must be removed so that 60% of the marbles in the bag will be green?

(A) 1
(B) 6
(C) 7
(D) 9
(E) 10

GIVEN: Start with 9 green marbles and 16 blue marbles

Let x = the number of BLUE marbles to remove
So, the NEW number of blue marbles remaining = 16 - x
The number of green marbles remaining = 9

How many blue marbles must be removed so that 60% of the marbles in the bag will be green?
We want: (number of GREEN marbles)/(TOTAL number of marbles) = 60%
Rewrite as: (number of GREEN marbles)/(TOTAL number of marbles) = 3/5

Plug in values to get: (9)/(16 - x + 9) = 3/5
Simplify to get: (9)/(25 - x) = 3/5
Cross multiply to get: (5)(9) = 3(25 - x)
Expand to get: 45 = 75 - 3x
Keep going: -30 = -3x
Solve: x = 10

Answer: E

Cheers,
Brent
Show more
9=0.6X
X=15
15-9=6
So, the number of blue marbles has to be 6.
16-y=6
y= 10

Posted from my mobile device
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,978
Own Kudos:
1,117
Posts: 38,978
Kudos: 1,117
The contents of a bag of marbles consist of 9 green marbles 09 Mar 2024, 23:16
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.
Moderators:
Bunuel
Math Expert
109821 posts
Krunaal
Tuck School Moderator
853 posts