GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 07 Dec 2019, 02:53

### 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

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

# In a certain school of dolphins, 20 dolphins eat neither

Author Message
TAGS:

### Hide Tags

Director
Joined: 25 Apr 2012
Posts: 651
Location: India
GPA: 3.21
In a certain school of dolphins, 20 dolphins eat neither  [#permalink]

### Show Tags

30 Jan 2014, 02:00
1
3
00:00

Difficulty:

65% (hard)

Question Stats:

60% (02:26) correct 40% (02:41) wrong based on 134 sessions

### HideShow timer Statistics

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.

_________________

“If you can't fly then run, if you can't run then walk, if you can't walk then crawl, but whatever you do you have to keep moving forward.”
Math Expert
Joined: 02 Sep 2009
Posts: 59587
Re: In a certain school of dolphins, 20 dolphins eat neither  [#permalink]

### Show Tags

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 [ 4.58 KiB | Viewed 2585 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).

_________________
Intern
Joined: 04 Jun 2018
Posts: 25
Location: Viet Nam
Concentration: Strategy, Operations
Schools: Rotman '22 (A\$)
GMAT 1: 610 Q47 V27
GMAT 2: 620 Q46 V29
GMAT 3: 680 Q47 V36
Re: In a certain school of dolphins, 20 dolphins eat neither  [#permalink]

### Show Tags

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).

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.
Manager
Joined: 09 Nov 2015
Posts: 153
Re: In a certain school of dolphins, 20 dolphins eat neither  [#permalink]

### Show Tags

25 May 2019, 01:50
Solution with detailed explanation is attached.
Attachments

Dolphins.docx [15.85 KiB]

Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 9850
Location: Pune, India
Re: In a certain school of dolphins, 20 dolphins eat neither  [#permalink]

### Show Tags

25 May 2019, 03:24
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.

This is what is given:

Attachment:

Screenshot 2019-05-25 at 15.49.53.png [ 43.63 KiB | Viewed 366 times ]

60 dolphins (green + yellow regions) => Eat sardines
Eat Both = 60 - 30 (Yellow) = 30 (green region)

A. 10 dolphins do not eat sardines.
Incorrect. We know that 20 eat neither. So this is not possible.

B. 20 dolphins eat both sardines and tuna.
Incorrect. We got that eat both = 30

C. 40 of the school dolphins that do not eat tuna, eat sardines.
Incorrect. 30 of those that do not eat tune, eat sardines (the yellow region).

D. There are 70 dolphins in the school.
Incorrect. No tuna = 50 and eat both = 30 so there must be at least 80 dolphins.

E. 30 of the dolphins eat tuna.
30 eat both. It is possible that 30 only eat tuna and there is no dolphin that eats only tuna.

_________________
Karishma
Veritas Prep GMAT Instructor

Re: In a certain school of dolphins, 20 dolphins eat neither   [#permalink] 25 May 2019, 03:24
Display posts from previous: Sort by