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In a certain school of dolphins, 20 dolphins eat neither

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In a certain school of dolphins, 20 dolphins eat neither  [#permalink]

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New post 30 Jan 2014, 02:00
1
00:00
A
B
C
D
E

Difficulty:

  65% (hard)

Question Stats:

56% (02:31) correct 44% (02:34) wrong based on 80 sessions

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In a certain school of dolphins, 20 dolphins eat neither sardines nor tuna. 50 of the dolphins do not eat tuna, and 60 eat sardines. Which of the following statements regarding the school of dolphins is possible?

A. 10 dolphins do not eat sardines.
B. 20 dolphins eat both sardines and tuna.
C. 40 of the school dolphins that do not eat tuna, eat sardines.
D. There are 70 dolphins in the school.
E. 30 of the dolphins eat tuna.

PS: Do not attempt the question if you are planning to take Economist Gmat Tutor free Simulation test.

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Re: In a certain school of dolphins, 20 dolphins eat neither  [#permalink]

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New post 30 Jan 2014, 02:23
1
WoundedTiger wrote:
In a certain school of dolphins, 20 dolphins eat neither sardines nor tuna. 50 of the dolphins do not eat tuna, and 60 eat sardines. Which of the following statements regarding the school of dolphins is possible?

A. 10 dolphins do not eat sardines.
B. 20 dolphins eat both sardines and tuna.
C. 40 of the school dolphins that do not eat tuna, eat sardines.
D. There are 70 dolphins in the school.
E. 30 of the dolphins eat tuna.

PS: Do not attempt the question if you are planning to take Economist Gmat Tutor free Simulation test.


Set a matrix:
Attachment:
Untitled.png
Untitled.png [ 4.58 KiB | Viewed 2022 times ]
As you can see only E is possible: if there are 0 dolphins who eat tuna but do not eat sardines, then 30 of the dolphins eat tuna (first row).

Answer: E.
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Re: In a certain school of dolphins, 20 dolphins eat neither  [#permalink]

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New post 10 Apr 2019, 00:54
Bunuel wrote:
WoundedTiger wrote:
In a certain school of dolphins, 20 dolphins eat neither sardines nor tuna. 50 of the dolphins do not eat tuna, and 60 eat sardines. Which of the following statements regarding the school of dolphins is possible?

A. 10 dolphins do not eat sardines.
B. 20 dolphins eat both sardines and tuna.
C. 40 of the school dolphins that do not eat tuna, eat sardines.
D. There are 70 dolphins in the school.
E. 30 of the dolphins eat tuna.

PS: Do not attempt the question if you are planning to take Economist Gmat Tutor free Simulation test.


Set a matrix:
Attachment:
Untitled.png
As you can see only E is possible: if there are 0 dolphins who eat tuna but do not eat sardines, then 30 of the dolphins eat tuna (first row).

Answer: E.


Hi Bunuel,

Could you please explain why B is incorrect?

If we set up an above matrix, there are 30 dolphins who eat both tuna and sardine. So we can conclude that 20 in 30 dolphins eat both tuna and sardine. I'm quite confused.
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Re: In a certain school of dolphins, 20 dolphins eat neither   [#permalink] 10 Apr 2019, 00:54
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In a certain school of dolphins, 20 dolphins eat neither

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