GRE Prep 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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
A jar contains 20 marbles: 4 red, 6 white and 10 blue
[#permalink]
06 Nov 2016, 13:11
06 Nov 2016, 13:11
3
5
Bookmarks
00:00
Question Stats:
42% (01:04) correct
57% (01:12) wrong based on 52 sessions
Hide Show timer Statistics
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
A. 6
B. 10
C. 12
D. 16
E. 18
Re: A jar contains 20 marbles: 4 red, 6 white and 10 blue
[#permalink]
06 Nov 2016, 13:40
06 Nov 2016, 13:40
5
Expert Reply
Here we have 10 Blue 6 White and 4 Red. The worst case scenario you pull all white and blue before you pull 2 red.
Hence minimum number of marbles you need the pull is all 10 white, 6 White and 2 Red.
Number of marbles to be removed = \(10 + 6 + 2\) = \(18\)
Hence minimum number of marbles you need the pull is all 10 white, 6 White and 2 Red.
Number of marbles to be removed = \(10 + 6 + 2\) = \(18\)
General Discussion
Target Test Prep Representative
Joined: 09 May 2016
Status:Head GRE Instructor
Affiliations: Target Test Prep
Posts: 183
Given Kudos: 114
Location: United States
Re: A jar contains 20 marbles: 4 red, 6 white and 10 blue
[#permalink]
06 May 2018, 16:39
06 May 2018, 16:39
2
Expert Reply
SJ wrote:
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
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
