Last visit was: 10 Jul 2025, 15:41 It is currently 10 Jul 2025, 15:41
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.
Close
Request Expert Reply
Confirm Cancel
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 10 July 2025
Posts: 102,631
Own Kudos:
Given Kudos: 98,170
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 102,631
Kudos: 740,181
 [21]
2
Kudos
Add Kudos
19
Bookmarks
Bookmark this Post
Most Helpful Reply
User avatar
aserghe1
Joined: 30 Mar 2017
Last visit: 26 Oct 2021
Posts: 84
Own Kudos:
166
 [8]
Given Kudos: 53
GMAT 1: 200 Q1 V1
Products:
GMAT 1: 200 Q1 V1
Posts: 84
Kudos: 166
 [8]
6
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
General Discussion
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 10 July 2025
Posts: 102,631
Own Kudos:
740,181
 [2]
Given Kudos: 98,170
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 102,631
Kudos: 740,181
 [2]
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
JeffTargetTestPrep
User avatar
Target Test Prep Representative
Joined: 04 Mar 2011
Last visit: 05 Jan 2024
Posts: 2,996
Own Kudos:
7,922
 [1]
Given Kudos: 1,646
Status:Head GMAT Instructor
Affiliations: Target Test Prep
Expert
Expert reply
Posts: 2,996
Kudos: 7,922
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
A jar contains 20 marbles: 4 red, 6 white and 10 blue. If you remove marbles one at a time, randomly, what is the minimum number that must be removed to be certain that you have at least 2 marbles of each colour?

A. 6
B. 10
C. 12
D. 16
E. 18

Assume the worst case scenario, that is, you remove all 10 blue marbles and all 6 white marbles; you still don’t have any marbles in red. However, if you remove 2 more marbles (and they must be red), then you will have at least 2 marbles of each color. Therefore, you need to remove a total of 18 marbles to ensure you will have at least 2 marbles of each color.

Answer: E
User avatar
dave13
Joined: 09 Mar 2016
Last visit: 23 Nov 2024
Posts: 1,114
Own Kudos:
Given Kudos: 3,851
Posts: 1,114
Kudos: 1,087
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
Bunuel
A jar contains 20 marbles: 4 red, 6 white and 10 blue. If you remove marbles one at a time, randomly, what is the minimum number that must be removed to be certain that you have at least 2 marbles of each colour?

A. 6
B. 10
C. 12
D. 16
E. 18

Check other Worst Case Scenario Questions from our Special Questions Directory to understand the concept better.

are such questions frequent on gmat ? :) the worst scenario :) how about the best scenario ? :)
avatar
siddharth19
Joined: 24 Jun 2017
Last visit: 10 Nov 2021
Posts: 27
Own Kudos:
Given Kudos: 354
Posts: 27
Kudos: 4
Kudos
Add Kudos
Bookmarks
Bookmark this Post
JeffTargetTestPrep
Bunuel
A jar contains 20 marbles: 4 red, 6 white and 10 blue. If you remove marbles one at a time, randomly, what is the minimum number that must be removed to be certain that you have at least 2 marbles of each colour?

A. 6
B. 10
C. 12
D. 16
E. 18

Assume the worst case scenario, that is, you remove all 10 blue marbles and all 6 white marbles; you still don’t have any marbles in red. However, if you remove 2 more marbles (and they must be red), then you will have at least 2 marbles of each color. Therefore, you need to remove a total of 18 marbles to ensure you will have at least 2 marbles of each color.

Answer: E

why do we start with the quantity highest in number ? as if we first remove 6 and 4 , then 2 from blue , result would be 12 . how is that wrong ?
thanks in advance
User avatar
azhrhasan
Joined: 13 Apr 2019
Last visit: 13 Sep 2024
Posts: 122
Own Kudos:
Given Kudos: 93
Location: Canada
Concentration: Marketing, Operations
GMAT 1: 690 Q49 V35
GPA: 3.5
WE:General Management (Retail: E-commerce)
Products:
GMAT 1: 690 Q49 V35
Posts: 122
Kudos: 164
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
A jar contains 20 marbles: 4 red, 6 white and 10 blue. If you remove marbles one at a time, randomly, what is the minimum number that must be removed to be certain that you have at least 2 marbles of each colour?

A. 6
B. 10
C. 12
D. 16
E. 18

worst case question:

(10+6+1)worst case +1

therefore, 18
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 37,379
Own Kudos:
Posts: 37,379
Kudos: 1,010
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
Moderators:
Math Expert
102631 posts
PS Forum Moderator
685 posts