Last visit was: 23 Apr 2026, 20:24 It is currently 23 Apr 2026, 20:24
Home
Messages
Tests
Schools
Events
Close
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
Your Progress

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
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
User avatar
enigma123
User avatar
Joined: 25 Jun 2011
Last visit: 16 Mar 2016
Posts: 392
Own Kudos:
19,859
 [46]
Given Kudos: 217
Status:Finally Done. Admitted in Kellogg for 2015 intake
Location: United Kingdom
Concentration: International Business, Strategy
GMAT 1: 730 Q49 V45
GPA: 2.9
WE:Information Technology (Consulting)
GMAT 1: 730 Q49 V45
Posts: 392
Kudos: 19,859
 [46]
The ratio of cats to dogs to birds to fish is 4:5:2:10. Ther 14 Dec 2013, 14:25
1
Kudos
Add Kudos
44
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

15% (low)

Question Stats:

84% (02:00) correct 16% (01:51) wrong based on 731 sessions

History

Date
Time
Result
Not Attempted Yet
The ratio of cats to dogs to birds to fish is 4:5:2:10. There are no other types of animals in the pet store. If there are 20 of one type of animal at the store then which of the following cannot be the total number of animals in the store?

A) 42
B) 63
C) 84
D) 105
E) 210
ShowHide Answer
Official Answer
B
Most Helpful Reply
User avatar
mikemcgarry
User avatar
Magoosh GMAT Instructor
Joined: 28 Dec 2011
Last visit: 06 Aug 2018
Posts: 4,474
Own Kudos:
30,880
 [10]
Given Kudos: 130
Expert
Expert reply
Posts: 4,474
Kudos: 30,880
 [10]
The ratio of cats to dogs to birds to fish is 4:5:2:10. Ther 14 Dec 2013, 14:36
6
Kudos
Add Kudos
4
Bookmarks
Bookmark this Post
enigma123
The ratio of cats to dogs to birds to fish is 4:5:2:10. There are no other types of animals in the pet store. If there are 20 of one type of animal at the store then which of the following cannot be the total number of animals in the store?

A) 42
B) 63
C) 84
D) 105
E) 210
Show more
Dear enigma123,
I'm happy to help. :-) This is a good question on ratio and proportions. See:
https://magoosh.com/gmat/2013/gmat-quant ... oportions/

The parts add up to 4 + 5 + 2 + 10 = 21, so we know that any possible number of total answers must be a multiple of 21. All five answer choices are multiples of 21:
(A) 42 = 21*2
(B) 63 = 21*3
(C) 84 = 21*4
(D) 105 = 21*5
(E) 210 = 21*10

The second stipulation is that the factor by which we are multiplying must bring one of the four numbers to 20.
4 time 5 is 20, so 5 is a possible multiple, and (D) is a possible total number.
5 time 4 is 20, so 4 is a possible multiple, and (C) is a possible total number.
2 time 10 is 20, so 10 is a possible multiple, and (E) is a possible total number.
10 time 2 is 20, so 2 is a possible multiple, and (A) is a possible total number.

By contrast, if we multiply everything by 3, none of the individual numbers becomes 20. Therefore, (B) is not a possible total number of animals, and this is the answer. OA = (B).

Does this make sense?
Mike :-)
General Discussion
avatar
PareshGmat
avatar
Joined: 27 Dec 2012
Last visit: 10 Jul 2016
Posts: 1,531
Own Kudos:
8,272
 [2]
Given Kudos: 193
Status:The Best Or Nothing
Location: India
Concentration: General Management, Technology
WE:Information Technology (Computer Software)
Posts: 1,531
Kudos: 8,272
 [2]
The ratio of cats to dogs to birds to fish is 4:5:2:10. Ther 11 Sep 2014, 03:31
1
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
enigma123
The ratio of cats to dogs to birds to fish is 4:5:2:10. There are no other types of animals in the pet store. If there are 20 of one type of animal at the store then which of the following cannot be the total number of animals in the store?

A) 42
B) 63
C) 84
D) 105
E) 210
Show more

Let the animal = x

4x + 5x + 2x + 10x = 21x

All options are already multiples of 21, so nothing can be ignored

Ratio is 4:5:2:10 >>> Note that the LCM of ratio's = 20. Already given that 20 animals are any of one type, so again all options have to be worked out.

Refer sheet below:
Attachment:
sap.png
sap.png [ 5.13 KiB | Viewed 23178 times ]

63 does not come up in calculation

Answer = B
User avatar
Abhishek009
User avatar
Board of Directors
Joined: 11 Jun 2011
Last visit: 17 Dec 2025
Posts: 5,903
Own Kudos:
5,452
 [4]
Given Kudos: 463
Status:QA & VA Forum Moderator
Location: India
GPA: 3.5
WE:Business Development (Commercial Banking)
Posts: 5,903
Kudos: 5,452
 [4]
The ratio of cats to dogs to birds to fish is 4:5:2:10. Ther 19 Jun 2017, 11:03
4
Kudos
Add Kudos
Bookmarks
Bookmark this Post
enigma123
The ratio of cats to dogs to birds to fish is 4:5:2:10. There are no other types of animals in the pet store. If there are 20 of one type of animal at the store then which of the following cannot be the total number of animals in the store?

A) 42
B) 63
C) 84
D) 105
E) 210
Show more
Total no of animals must be a multiple of \(4+5+2+10 = 21\) , all the options satisfies the conditions...

If the total no of cats is 20 , total no of animals is 105 ( Option D )
If the total no of dogs is 20 , total no of animals is 84 ( Option C )
If the total no of birds is 20 , total no of animals is 210 ( Option E )
If the total no of fist is 20 , total no of animals is 42 ( Option A )

So, the correct answer will be (B)
User avatar
JeffTargetTestPrep
User avatar
Target Test Prep Representative
Joined: 04 Mar 2011
Last visit: 05 Jan 2024
Posts: 2,974
Own Kudos:
8,710
 [1]
Given Kudos: 1,646
Status:Head GMAT Instructor
Affiliations: Target Test Prep
Expert
Expert reply
Posts: 2,974
Kudos: 8,710
 [1]
The ratio of cats to dogs to birds to fish is 4:5:2:10. Ther 06 Jul 2017, 17:45
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
enigma123
The ratio of cats to dogs to birds to fish is 4:5:2:10. There are no other types of animals in the pet store. If there are 20 of one type of animal at the store then which of the following cannot be the total number of animals in the store?

A) 42
B) 63
C) 84
D) 105
E) 210
Show more

We are given that the ratio of cats to dogs to birds to fish is 4 : 5 : 2 : 10 = 4x : 5x : 2x : 10x.

Thus, the total number of animals is 21x.

Let’s analyze each answer choice:

A) 42

21x = 42

x = 2

Since 20 is a multiple of 2 and, in particular, the number of fish = 10x = 10(2) = 20, there can be 42 animals in the store.

B) 63

21x = 63

x = 3

Since 20 is not a multiple of 3, there cannot be 63 animals in the store.

Alternate solution:

We are given that the ratio of cats to dogs to birds to fish is 4 : 5 : 2 : 10 = 4x : 5x : 2x : 10x.

Thus, the total number of animals is 21x.

Since the number of one type of animal is 20, we can see that x could be 5, 4, 10, and 2, respectively, for the number of cats, dogs, birds, and fish to be 20.

Since the total number of animals is 21x, the total number of animals could be 105, 84, 210, and 42. We see that all of these 4 numbers are in the given answer choices. However, the answer choice of 63 is not one of these 4 numbers, so it can’t be the total number of animals.

Answer: B
User avatar
TimeTraveller
User avatar
Joined: 28 Jun 2015
Last visit: 29 Jul 2017
Posts: 237
Own Kudos:
361
Given Kudos: 47
Concentration: Finance
GPA: 3.5
Posts: 237
Kudos: 361
The ratio of cats to dogs to birds to fish is 4:5:2:10. Ther 06 Jul 2017, 18:43
Kudos
Add Kudos
Bookmarks
Bookmark this Post
If 4 corresponds to 20: 20+25+10+50 = 105.

If 5 corresponds to 20: 16+20+8+40 = 84.

If 2 corresponds to 20: 40+50+20+100 = 210.

If 10 corresponds to 20: 8+10+4+20 = 42.

Ans - B.
User avatar
BrentGMATPrepNow
User avatar
Major Poster
Joined: 12 Sep 2015
Last visit: 31 Oct 2025
Posts: 6,733
Own Kudos:
36,451
 [2]
Given Kudos: 799
Location: Canada
Expert
Expert reply
Posts: 6,733
Kudos: 36,451
 [2]
The ratio of cats to dogs to birds to fish is 4:5:2:10. Ther 03 Feb 2021, 08:15
1
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
enigma123
The ratio of cats to dogs to birds to fish is 4:5:2:10. There are no other types of animals in the pet store. If there are 20 of one type of animal at the store then which of the following cannot be the total number of animals in the store?

A) 42
B) 63
C) 84
D) 105
E) 210
Show more

Given: The ratio of cats to dogs to birds to fish is 4 : 5 : 2 : 10
In this original ratio, the sum of all parts = 4 + 5 + 2 + 10 = 21

If we multiply all parts by 2, we get the EQUIVALENT ratio: 8 : 10 : 4 : 20. So, there COULD be 8 cats, 10 dogs, 4 birds, and 20 fish.
In this case, the TOTAL number of animals = (2)(21)= 42
Eliminate A.

If we multiply all parts of the original ratio by 5, we get the EQUIVALENT ratio: 20 : 25 : 10 : 50.
In this case, the TOTAL number of animals = (5)(21)= 105
Eliminate D.

If we multiply all parts of the original ratio by 4, we get the EQUIVALENT ratio: 16 : 20 : 8 : 40.
In this case, the TOTAL number of animals = (4)(21)= 84
Eliminate C.

If we multiply all parts of the original ratio by 10, we get the EQUIVALENT ratio: 40 : 50 : 20 : 100.
In this case, the TOTAL number of animals = (10)(21)= 210
Eliminate E.

By the process of elimination, the correct answer is B
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,960
Own Kudos:
1,117
Posts: 38,960
Kudos: 1,117
The ratio of cats to dogs to birds to fish is 4:5:2:10. Ther 25 Sep 2025, 15:54
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.
Moderators:
Bunuel
Math Expert
109785 posts
Krunaal
Tuck School Moderator
853 posts