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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
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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 ? :)
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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
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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
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