Last visit was: 21 Apr 2026, 05:51

It is currently 21 Apr 2026, 05:51

Toolkit

Practice Tests

Quantitative Questions

Problem Solving (PS)

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

Request Expert Reply

Confirm Cancel

Apr 16
Sneak Peek: $200 Off GMAT Prep
12:00 PM EDT
-
11:59 PM EDT
You’re first to know: Save $200 on GMAT prep starting tomorrow, 4/13. Get 6 official practice tests and study with real questions. Be ready to save!
Apr 26
Score High on the GMAT with Target Test Prep
10:00 AM EDT
-
11:00 AM EDT
The Target Test Prep course represents a quantum leap forward in GMAT preparation, a radical reinterpretation of the way that students should study. Try before you buy with a 5-day, full-access trial of the course for FREE!
Apr 27
Try OnDemand GMAT Masterclass
11:00 AM EDT
-
12:00 PM EDT
Prefer video-based learning? The Target Test Prep OnDemand course is a one-of-a-kind video masterclass featuring 400 hours of lecture-style teaching by Scott Woodbury-Stewart, founder of Target Test Prep and one of the most accomplished GMAT instructors
Apr 28
Join - GMAT Day!
08:00 AM PDT
-
11:00 AM PDT
Whether you are just beginning your MBA journey or fine-tuning your path to a 700+ score, GMAT Day is designed to give you a competitive edge.

Back to Forum

Create Topic

12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary

1 2 3 4 5

Heix

Joined: 21 Feb 2024

Last visit: 13 Apr 2026

Posts: 460

Own Kudos:

164

[1]

Given Kudos: 63

Location: India

Concentration: Finance, Entrepreneurship

Schools: Ross MM "26 NUS Columbia '27

GMAT Focus 1: 485 Q76 V74 DI77 Verified score

GPA: 3.4

WE:Accounting (Finance)

Products:

Schools: Ross MM "26 NUS Columbia '27

GMAT Focus 1: 485 Q76 V74 DI77 Verified score

Posts: 460

Kudos: 164

[1]

24 Dec 2024, 22:36

Kudos

Bookmarks

Show Spoiler

Attachment:

GMAT-Club-Forum-95o7echq.jpeg [ 141.76 KiB | Viewed 503 times ]

SafSin28

Joined: 16 Aug 2022

Last visit: 20 Apr 2026

Posts: 84

Own Kudos:

[1]

Given Kudos: 60

Posts: 84

Kudos: 67

[1]

25 Dec 2024, 00:22

Kudos

Bookmarks

First we make the matrix of the problem: Animals=Mammals+Birds here. So it takes the following situation:

5z+4z=630, 9z=630, z=70, Now we can find mammals:

So, Tagged mammals/tagged birds=6/1,
[350-x]/x=6, x=50. 280-4x=280-200=80

Show Spoiler

Attachment:

GMAT-Club-Forum-xvngkqd4.png [ 23.57 KiB | Viewed 488 times ]

Attachment:

GMAT-Club-Forum-zctym1b1.png [ 8.38 KiB | Viewed 503 times ]

Prakhar9802

Joined: 07 Aug 2023

Last visit: 15 Apr 2026

Posts: 63

Own Kudos:

[1]

Given Kudos: 1

Posts: 63

Kudos: 68

[1]

25 Dec 2024, 00:51

Kudos

Bookmarks

Total animals = 630
5 out of every 9 are tagged. We can take this as, we have groups of 9 each, and in each group 5 are tagged.

Total groups = 630/9 = 70

In each group, 5 are tagged = 70*5 = 350

Ratio of tagged mammals to tagged birds = 6:1
6x+1x = 350
7x = 350
x=50

therefore, tagged mammals 6x = 300
Tagged birds = 1x = 50

But, only B/5 were tagged, therefore, B/5 = 50
B = 250

Therefore, mammals = 630 - 250 = 380

Untagged mammals = total mammals - tagged mammals
Untagged mammals = 380 - 300 = 80

FINAL ANSWER - Option B

Bunuel

12 Days of Christmas 2024 - 2025 Competition with $40,000 of Prizes

At a wildlife sanctuary, there are 630 animals, and 5 out of every 9 animals are tagged. Of the birds, only a fifth have been tagged. Among the tagged animals, the ratio of mammals to birds is 6:1. If the sanctuary houses only mammals and birds, how many mammals are untagged?

A. 50
B. 80
C. 120
D. 200
E. 300

This question was provided by GMAT Club
for the 12 Days of Christmas Competition

Win $40,000 in prizes: Courses, Tests & more

D3N0

Joined: 21 Jan 2015

Last visit: 19 Mar 2026

Posts: 585

Own Kudos:

607

[1]

Given Kudos: 132

Location: India

Concentration: Operations, Technology

Schools: Smeal'21 (WD) Arizona State'21 (A$) Simon '21 (WD)

GMAT 1: 620 Q48 V28 Verified score

GMAT 2: 690 Q49 V35 Verified score

WE:Operations (Retail: E-commerce)

Products:

Schools: Smeal'21 (WD) Arizona State'21 (A$) Simon '21 (WD)

GMAT 2: 690 Q49 V35 Verified score

Posts: 585

Kudos: 607

[1]

25 Dec 2024, 01:03

Kudos

Bookmarks

Ans: B

A. 50
B. 80
C. 120
D. 200
E. 300

Given: Total 630, 5 out of 9 animals are tagged = 630*(5/9) = 350 are tagged (total T)
Total UT = 630-350 = 280
among the tagged, Ratio of mammals to birds is= Mt : Bt :: 6 : 1 ==> Mt = 350*(6/7) = 300 and Bt = 50
of the birds only a 5th have been tagged = Bt = B*(1/5)= 50 this will give us B = 250
So B untagged = 250-50 = 200

	M	B	Total
T	300	50	350
UT	?=	200	280
Total		250	630

We get UT = 80

Navya442001

Joined: 26 Jan 2024

Last visit: 17 Nov 2025

Posts: 67

Own Kudos:

[1]

Given Kudos: 1

Products:

Posts: 67

Kudos: 72

[1]

25 Dec 2024, 01:48

Kudos

Bookmarks

Bunuel

This question was provided by GMAT Club
for the 12 Days of Christmas Competition

Win $40,000 in prizes: Courses, Tests & more

The total number of animals in the sanctuary is 630. We are told that 5 out of every 9 animals are tagged. Hence, the number of tagged animals is:
Tagged animals=(5/9)×630=350
Untagged animals=630−350=280

Let M be the total number of mammals and B be the total number of birds. Since the sanctuary houses only mammals and birds, we know:
M+B=630
Among the tagged animals, the ratio of mammals to birds is 6:1. Thus, of the 350 tagged animals:

The number of tagged mammals is (6/(6+1))×350=(6/7)×350=300
The number of tagged birds is (1/7)×350=50

Only a fifth of the birds are tagged. Therefore, the total number of birds is:
Total birds=Tagged birds/(1/5)=50×5=250

Since the total number of animals is 630 and there are 250 birds, the number of mammals is:
M=630−250=380

Out of the 380 mammals, 300 are tagged. Hence, the number of untagged mammals is:
Untagged mammals=380−300=80
The number of untagged mammals is 80
Correct option: B.

Devaditya

Joined: 13 Nov 2023

Last visit: 22 Mar 2026

Posts: 15

Own Kudos:

[1]

Given Kudos: 39

Location: India

Concentration: International Business, Economics

Schools: IIM Sloan (MIT) ESADE NUS

GPA: 3.5

WE:Operations (Retail: E-commerce)

Schools: IIM Sloan (MIT) ESADE NUS

Posts: 15

Kudos: 11

[1]

25 Dec 2024, 02:21

Kudos

Bookmarks

Total animals: 630

Tagged animals: 5/9×630 =350

Untagged animals: 630−350 =280

Among the tagged animals, the ratio of mammals to birds is 6:1. This means:

Tagged mammals:
6/7×350 =300

Tagged birds:
1/7×350= 50

Of the birds, only a fifth have been tagged. So, the total number of birds is:

Total birds:
50×5=250

Since the sanctuary houses only mammals and birds:

Total mammals: 630−250=380

Now, we need to find the number of untagged mammals:

Untagged mammals: 380−300=80

Therefore, the number of untagged mammals is B. 80.

Oppenheimer1945

Joined: 16 Jul 2019

Last visit: 16 Apr 2026

Posts: 786

Own Kudos:

663

[1]

Given Kudos: 236

Location: India

Schools: INSEAD '26 (D) ISB '27 (D) IIMB '26 (A) IIMA '26 (A) HEC '26 (D) LBS '26 IESE '27 (D) Fuqua '27 (WL) Tepper '27 (WL)

GMAT Focus 1: 645 Q90 V76 DI80 Verified score

GPA: 7.81

Schools: INSEAD '26 (D) ISB '27 (D) IIMB '26 (A) IIMA '26 (A) HEC '26 (D) LBS '26 IESE '27 (D) Fuqua '27 (WL) Tepper '27 (WL)

GMAT Focus 1: 645 Q90 V76 DI80 Verified score

Posts: 786

Kudos: 663

[1]

25 Dec 2024, 02:31

Kudos

Bookmarks

350 = tagged animals
300= tagged mammals, tagged birds =50
Total birds = 250
This untagged mammals = 630-350-200= 80

Ans b

prantorboni

Joined: 28 Nov 2020

Last visit: 03 Nov 2025

Posts: 147

Own Kudos:

150

[1]

Given Kudos: 221

Products:

Posts: 147

Kudos: 150

[1]

25 Dec 2024, 03:14

Kudos

Bookmarks

At a wildlife sanctuary, there are 630 animals, and 5 out of every 9 animals are tagged. Of the birds, only a fifth have been tagged. Among the tagged animals, the ratio of mammals to birds is 6:1. If the sanctuary houses only mammals and birds, how many mammals are untagged?

5 out of every 9 animals are tagged. So, there are a total= 630/9x5= 350 tagged animals.

Among the tagged animals, the ratio of mammals to birds is 6:1. So, there are a total of 350/7x6= 300:mammals and 350/7x1= 50 birds.

Of the birds, only a fifth have been tagged. Let’s assume, there are a total of x birds, then, x/5= 50, x= 250. Which means, there are a total of 250 birds among which 200 are tagged and there. Total of 630-250= 380 mammals among which 300 are tagged. So, the untagged mammals are380-300= 80.

Answer: B. 80.

LastHero

Joined: 15 Dec 2024

Last visit: 12 Dec 2025

Posts: 134

Own Kudos:

147

[1]

Given Kudos: 1

Posts: 134

Kudos: 147

[1]

25 Dec 2024, 03:42

Kudos

Bookmarks

From the data:
birds/5 + 6*birds/5=350
birds=250

mammals = 630-birds = 630-250 = 380
mammals = mammals tagged + mammals untagged = 6*birds/5 + mammals untagged = 300 + mammals untagged

300 + mammals untagged = 380
mammals untagged = 80

Answer B

Shruuuu

Joined: 21 Nov 2023

Last visit: 19 Jan 2026

Posts: 70

Own Kudos:

[1]

Given Kudos: 99

Location: India

Schools: ISB '27 (A)

GMAT Focus 1: 655 Q83 V86 DI78 Verified score

Schools: ISB '27 (A)

GMAT Focus 1: 655 Q83 V86 DI78 Verified score

Posts: 70

Kudos: 95

[1]

25 Dec 2024, 03:53

Kudos

Bookmarks

total animals = 630
tagged = 5/9 * 630 = 350
Tagged birds = 1/5 * total birds
Tagged Mammals / Tagged Birds = 6/1 = i.e. (350 * 6/7) & (350*1/7) = 300 & 50 respectively
50 = 1/5 * Total Birds
250 = Birds
Mammals = 630 - Birds = 630 - 250 = 380
Untagged mammals = 380 - 300 = 80

IMO B

Bunuel

This question was provided by GMAT Club
for the 12 Days of Christmas Competition

Win $40,000 in prizes: Courses, Tests & more

HelpfulChocolate

Joined: 21 Dec 2024

Last visit: 26 Dec 2024

Posts: 21

Own Kudos:

[1]

Given Kudos: 1

GRE 1: Q168 V158 Verified score

Posts: 21

Kudos: 24

[1]

25 Dec 2024, 04:34

Kudos

Bookmarks

Bunuel

This question was provided by GMAT Club
for the 12 Days of Christmas Competition

Win $40,000 in prizes: Courses, Tests & more

In 630 animals, 5 out of 9 are tagged. So, the ratio of Tagged to Untagged is 5:4
9x = 630; x = 70
Number of Tagged animals to Untagged = 350:280

Of the birds, 1/5th have been tagged. The ratio of Tagged to Untagged birds is 1:4

Among the tagged animals, the ratio of mammals to birds is 6:1

How many untagged mammals are there?

Ratio of tagged mammals to tagged birds = 6:1
7x = 350; x = 50
Number of tagged mammals to tagged birds = 300:50

Ratio of tagged birds to untagged birds = 1:4
If there are 50 tagged birds, then the number of untagged birds is 50 * 4 = 200

Number of untagged mammals = Number of untagged animals - Number of untagged birds
280 - 200 = 80

Type/Tag Status	Mammal	Bird	Animal
Tagged	300	50	350
Untagged	80	200	280
Total	380	250	630

[b] is the correct answer.[/b]

pintukr

Joined: 03 Jul 2022

Last visit: 20 Apr 2026

Posts: 1,729

Own Kudos:

1,148

[1]

Given Kudos: 24

GMAT 1: 680 Q49 V34 Verified score

Products:

GMAT 1: 680 Q49 V34 Verified score

Posts: 1,729

Kudos: 1,148

[1]

25 Dec 2024, 04:50

Kudos

Bookmarks

At a wildlife sanctuary, there are 630 animals, and 5 out of every 9 animals are tagged. Of the birds, only a fifth have been tagged. Among the tagged animals, the ratio of mammals to birds is 6:1. If the sanctuary houses only mammals and birds, how many mammals are untagged?

A. 50
B. 80
C. 120
D. 200
E. 300

For 630 animals, tagged : untagged = 5 : 4

so, tagged animals = 350
un-tagged animals = 280..............(1)

For, tagged animals (350),
mammals : birds = 6 : 1

so, tagged mammals= 300
tagged birds = 50

Since, tagged birds (1/5th of total birds); so, un-tagged birds = 200..............(2)

Un-tagged mammals = 280-200 = 80

(B) is the CORRECT answer

Nsp10

Joined: 22 May 2023

Last visit: 30 Mar 2026

Posts: 125

Own Kudos:

[1]

Given Kudos: 112

Location: India

Schools: IE Schulich

GPA: 3.0

Products:

Schools: IE Schulich

Posts: 125

Kudos: 91

[1]

25 Dec 2024, 05:34

Kudos

Bookmarks

just make one matrix

ratio of tagged to total is 5:9 that is tagged to untagged is 5:4 by this we can calculate total tagged and untagged animals which is 350 and 280,
1/5th birds are tagged which means 4/5th birds are untagged,
and among the tagged the ratio of mammals to birds is 6:1 that is out of 350 tagged 300 are mammals and 50 are birds,
thus we can make this
T UT Total
Bird 50 200 250
Mammal 300 80 380
Total 350 280 630,
so 80 is our desired answer.

Bunuel

This question was provided by GMAT Club
for the 12 Days of Christmas Competition

Win $40,000 in prizes: Courses, Tests & more

Mardee

Joined: 22 Nov 2022

Last visit: 02 Feb 2026

Posts: 225

Own Kudos:

191

[1]

Given Kudos: 20

Posts: 225

Kudos: 191

[1]

25 Dec 2024, 05:38

Kudos

Bookmarks

Total number of animals in the wildlife sanctuary is 630
5 out of every 9 animals are tagged =>
Total tagged animals = 5/9 ×630=350
Total untagged animals = 630−350=280

A fifth of the birds are tagged:

Let the number of birds be b
Tagged birds =1/5×b=0.2b
Untagged birds = b−0.2b=0.8b

Among the tagged animals, the ratio of mammals to birds is 6:1 =>

Tagged mammals = 6×(Tagged birds)=6×0.2b=1.2b
Total tagged animals = Tagged mammals + Tagged birds = 1.2b+0.2b=1.4b
=> 1.4b=350
=> b=250

Mammals = Total Animals - Birds = 630 - 250 = 380
=> Tagged Birds = 0.2b = 0.2x250 = 50
=> Tagged mammals = 350 - 50 = 300
=> Untagged mammals = Total mammals - Tagged mammals = 380-300 = 80

SunnyPoddar

Joined: 21 Nov 2020

Last visit: 09 Apr 2026

Posts: 29

Own Kudos:

[1]

Given Kudos: 2

Posts: 29

Kudos: 24

[1]

25 Dec 2024, 05:44

Kudos

Bookmarks

Bunuel

This question was provided by GMAT Club
for the 12 Days of Christmas Competition

Win $40,000 in prizes: Courses, Tests & more

Total Animals = 630
Tagged animals = (5/9)*630 = 350

Untagged animal = 630 - 350 = 280

M : B = 6:1 (Tagged)
M+B = 350 (tagged)

M = 300, B = 50 (tagged)

We are given only 1/5 of Birds are tagged and we know total tagged birds are 50. This makes the Total birds as 50*5 = 250.

Mammal + Birds = 630
Mammal + 250 = 630
Mammal = 380

We already know tagged mammals are 300 so, 380-300 = 80 untagged mammals.

__Poisonivy__

Joined: 24 Feb 2024

Last visit: 08 Apr 2025

Posts: 53

Own Kudos:

[1]

Given Kudos: 2

Posts: 53

Kudos: 56

[1]

25 Dec 2024, 06:34

Kudos

Bookmarks

Total no. of animals= 630
n0. of animals tagged= 630x5/9= 350
no. of animals untagged= 630-350= 280

Let no. of tagged mammals= Tm
and no. of tagged bird= Tb

So, Tm/Tb= 6/1=> [Tm=6Tb].
Tm+ Tb= 350=> 6Tb+Tb= 350=> 7Tb=350=> [Tb=50, Tm=300]

Let total no. of birds= B
and no. of Mammals= M

Given, only 1/5th of the Birds were tagged, so 1/5xB= 50=> B=250.

So, total no. of Mammals M= 630-B= 380.

So, M= 380, Tm= 300.
Therefor, no. of untagged mammals= M-Tm= 80.

Ans. opt. B (80)

GMATNextStep

Joined: 01 Aug 2023

Last visit: 20 Apr 2026

Posts: 34

Own Kudos:

[1]

Given Kudos: 1

GMAT Focus 1: 715 Q85 V88 DI84 (Online) Verified score

Products:

GMAT Focus 1: 715 Q85 V88 DI84 (Online) Verified score

Posts: 34

Kudos: 36

[1]

25 Dec 2024, 06:50

Kudos

Bookmarks

Quote:

	tagged	not tagged	Total
birds	b/5	4b/5	b
mammals	m
Total	350	280	630

630 animals * 5/9 = 350 tagged animals, remaining 280 not tagged
ratio tagged mammals to birds 6:1 -> m : (b/5) = 6 : 1 -> 5m/b = 6 : 1 -> m = 6b/5. Substitute this into formula b/5 + m = 250 to solve for b = 250
-> 4b/5 = 200 -> not tagged mammals = 280 - 200 = 80

Choose B

rns2812

Joined: 10 Nov 2024

Last visit: 28 Aug 2025

Posts: 50

Own Kudos:

[1]

Given Kudos: 14

Posts: 50

Kudos: 51

[1]

25 Dec 2024, 07:09

Kudos

Bookmarks

Total animals = 630
5 out of 9 are tagged
Tagged animals = 70 * 5 = 350
6:1 = Tagged mammals : tagged birds = 300 : 50

Only 1/5th of birds are tagged
Total number of birds = 5 * 50 = 250

Total number of mammals = 380
Untagged mammals = 380 - 300 = 80

OPTION B

Bunuel

This question was provided by GMAT Club
for the 12 Days of Christmas Competition

Win $40,000 in prizes: Courses, Tests & more

nousernamefine

Joined: 14 Jan 2024

Last visit: 11 Apr 2026

Posts: 38

Own Kudos:

[1]

Given Kudos: 131

Location: India

Schools: Columbia '27 Wharton '27 Stanford '27

GPA: 4

Schools: Columbia '27 Wharton '27 Stanford '27

Posts: 38

Kudos: 32

[1]

25 Dec 2024, 07:39

Kudos

Bookmarks

Animals tagged= 630*(5/9)=350
Out of tagged Animals Mammal : Bird=6:1 (300 :50)
Tagged Birds=50 (1/5 of Birds were tagged)
Total Birds = 50*5= 250
Mammals = Animals-Bird= 630-250 = 380
Mammals Total= 380
Mammals tagged= 300
Untagged Mammals= 80 (Ans- B)

Thanks!

Bunuel

This question was provided by GMAT Club
for the 12 Days of Christmas Competition

Win $40,000 in prizes: Courses, Tests & more

BatrickPatemann

Joined: 29 May 2024

Last visit: 15 Apr 2026

Posts: 64

Own Kudos:

[1]

Given Kudos: 153

Location: Spain

Schools: HEC (D) ESSEC MiF '26 (S)

GPA: 6.74

Schools: HEC (D) ESSEC MiF '26 (S)

Posts: 64

Kudos: 55

[1]

25 Dec 2024, 08:01

Kudos

Bookmarks

5/9*630 =350 animals are tagged
1/5B are tagged and 4/5B are untagged

Tagged Mammals to tagged birds 6:1 and given that there's only these two types of animals we know that 6/7*350 =300 mammals tagged and 50 birds tagged

1/5B = 50, thus Birds are 250 -> untagged birds are 4/5*250 = 200

Thus untagged mammals are (630-350) - 200 =80