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Math Expert
Joined: 02 Sep 2009
Posts: 65187
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A jar contains 20 marbles: 4 red, 6 white and 10 blue. If you remove
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 03 May 2018, 01:21
Question Stats:
58% (01:13) correct 42% (01:39) wrong based on 190 sessions
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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
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Math Expert
Joined: 02 Sep 2009
Posts: 65187
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Re: A jar contains 20 marbles: 4 red, 6 white and 10 blue. If you remove
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03 May 2018, 01:27
Bunuel 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 Check other Worst Case Scenario Questions from our Special Questions Directory to understand the concept better.
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Manager
Joined: 30 Mar 2017
Posts: 106
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Re: A jar contains 20 marbles: 4 red, 6 white and 10 blue. If you remove
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03 May 2018, 13:54
No math necessary. If you remove 10 marbles, all of them could be blue. If you remove 16 marbles, all of them could by blue or white. If you remove 18 marbles, you will definitely have at least 2 of each color.
Answer: E
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Target Test Prep Representative
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2799
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Re: A jar contains 20 marbles: 4 red, 6 white and 10 blue. If you remove
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07 May 2018, 09:33
Bunuel 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 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
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Joined: 09 Mar 2016
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Re: A jar contains 20 marbles: 4 red, 6 white and 10 blue. If you remove
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09 May 2018, 07:53
Bunuel wrote: Bunuel 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 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 ?
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Intern
Joined: 24 Jun 2017
Posts: 30
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Re: A jar contains 20 marbles: 4 red, 6 white and 10 blue. If you remove
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03 Jun 2019, 11:35
JeffTargetTestPrep wrote: Bunuel 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 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
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Manager
Joined: 13 Apr 2019
Posts: 178
Location: India
Concentration: Marketing, Operations
Schools: Ross '22, Stern '22, Anderson '22, Darden '21, Johnson '22, Kelley '22, INSEAD Jan '20, IESE '22, HKUST '22, ISB '21, Rotman '22, NUS '22, CEIBS '22, NTU '21, Rutgers '22
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WE: General Management (Retail)
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Re: A jar contains 20 marbles: 4 red, 6 white and 10 blue. If you remove
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04 Aug 2019, 04:21
Bunuel 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 worst case question: (10+6+1)worst case +1 therefore, 18
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Re: A jar contains 20 marbles: 4 red, 6 white and 10 blue. If you remove
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04 Aug 2019, 04:21
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