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Hi everyone,

This is an overlap question (I will use double matrix in order to solve that question),
I will show each step of solving:

TaggedUnTaggedTotal
BirdsB/54B/5B
MamalsM
Total5x4x630
9x=630
x=70

TaggedUnTaggedTotal
BirdsB/5=y4B/5B
Mamals6yM
Total350280630
y+6y = 350
7y=350
y=50

TaggedUnTaggedTotal
Birds504B/5B
Mamals300
Total350280630
50*4=200

TaggedUnTaggedTotal
Birds50200250
Mamals30080380
Total350280630

B - 80 is our answer.
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Tagged Animals = 5/9*630 = 350

Not Tagged = 280

1/5 Birds = 1/7 * 350
Birds = 250
Mammals = 630 - 250 = 380
Tagged Mammals = 300

Not Tagged = 380 - 300 = 80

IMO 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

 

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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

 

Total animal = 630
Tagged animals = 5/9 * 630 = 350
Untagged animals = 630 - 350 = 280
Tagged mammals = 6/7*350 = 300
Tagged birds = 50
Untagged birds = (50*5) - 50 = 200
Untagged mammals = 280 - 200 = 80
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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

 





Let the number of birds = x
Tagged Birds = x/5

As the ratio of tagged animals to not tagged animals is 5 : 9, the number of tagged animals = 350, and the number of not tagged animals = 280

We can plot the information given in a 2 * 2 matrix as shown below



7x/5 = 350

x = 250

Mammals = 630 - 250 = 380

4x/5 = 200

Not tagged mammals = 280 - 200 = 80

Option B
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BirdsMammals
tagged animalsx6x350
untagged animals280
5x630

Every 5 out of every 9 animals are tagged. The number of tagged animals is [5][/9] of 630 equal to 350
Let the number of tagged birds be 5x

Solving for x gives x=50
BirdsMammals
tagged animals50300350
untagged animals280
250380630

That gives number of untagged mammals to 80

Ans is 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

 

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Total animals = 630
5/9 are tagged => 350 tagged, 280 untagged

tagged mammals/tagged birds = 6/1
7x = 350
x = 50
=> tagged birds = 50
=> tagged mammals = 300

1/5 birds are tagged
1/5(total birds) = 50
total birds = 250
total mammals = 630 - 250 = 380

Untagged mammals = 380-300 = 80

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

 

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Total 630
tagged animals: 630 x 5/9 =350
among tagged, mammals: 350 x 6/7 =300 and birds = 350 x 1/7 = 50
1/5 of birds = tagged birds = 50 . hence total birds = 250
hence 200 birds are untagged

untagged animals: 630 x 4/9 =280
so untagged mammals = 280 - 200 = 80
B is correct



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

 

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The stem tells us that;
  • At a wildlife sanctuary, there are 630 animals
  • 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
  • the sanctuary houses only mammals and birds

And we have to select;
  • how many mammals are untagged

Tagged animals=5/9*630=350

Among them, mammals = 6/7*350=300
and, birds =350-300=50

Tagged birds=total birds/5
So, Total birds= 50*5=250

Total animals= total birds+total mammals
630=250+ total mammals

total mammals=630-250=380
Since tagged mammals=300

Untagged mammals=80

Answer is B
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630 animals

5/9 (650) are tagged = 350

Among the tagged animals, mammals outnumber birds 6 to 1
so we get tagged birds = 50

If 1/5 of the total bird population is tagged and we know the tagged birds number
So, birds = 250
mammals = 380

Tagged mammals = total tagged animals - tagged birds
= 350 - 50 = 300
We are asked for untagged animals = 380 - 300 = 80

(B) is the answer

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

 

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The answer is option B.

Total = 630 5/9 of animals = 5/9(630) = 350 = tagged animals

Among the tagged animals ratio of mammals to birds are in the ratio 6:1 so 6/7*350 = 300 =tagged mammals

similarly 1/7(350) = 50 = tagged birds

1/5 (birds) = tagged birds = 5*50 = total birds = 250

Untagged birds = total - tagged = 250 - 50 = 200

Total mammals = total - birds = 630 - 250 = 380

Untagged mammals = total mammals - tagged mammals = 380 - 300 =80
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Total animals= 630
Tagged animals = \(\frac{5}{9}\) *630 = 350
Let total mammals be m
# of total birds = 630-m

Tagged birds =\(\frac{[630-m]}{5}\)
Tagged mammals = 350 - \(\frac{[630-m]}{5}\)

Let, \(\frac{[630-m]}{5}\) be x

Writing equation for ratio of tagged mammals to tagged birds (6:1)

\(\frac{(350-x)}{x}\)= \(\frac{6}{1}\)

Solving for x gives, x = 50

Tagged mammals = 350-x = 300

Solving for x = \(\frac{[630-m]}{5}\) = 50

Total mammals (m)= 380

Untagged mammals = 380 - 300
=80

Answer is (B)
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B
Total 630 animals

5 out of 9 are tagged, which means 5 : (9-5) = tagged:untagged

Hence tagged = 350 animals, untagged = 280 animals

Among tagged mammals to birds is 6:1
tagged mammals = 6/7 * (350) = 300
tagged birds = 350 - 300 = 50

among total birds 1/5 th are tagged
so 1/5 * (total birds) = 50
total birds = 250

untagged birds = 200
untagged mammals = 280 - 200 = 80 untagged mammals

Hence 80 mammals are untagged
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

 

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Given total animals =630
total tagged = 5/9 (630) = 350
in tags mammels to bird = 300, 50 (6:1)
given only 1/5th of birds are tagged, hence total birds is 5x50 = 250
As total mammals = 630 - 250 = 380 and
300 of them been tagged

80 are untagged mammals Option B
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tagged animals ratio, mammals:bird=6:1
(5/9) * 630 = 350 animals are tagged.

Hence tagged mammals= 300 {6/7 * 350}
tagged birds=50 {1/7 * 350}

Given 1/5 of birds are tagged this means Total birds =250
Hence mammals = 630-250 =380
Untagged mammals = 80
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Total: 630
Total tagged = 5/9 * 630 = 350

Total bird = x
Tagged bird = x/5




IMO, B

Total mammals = 630 - x
Tagged mammals = 350 - x/5
Untagged mammals = (630 - x) - (350 -x/5) => need to find this

We have: (350 - x/5) / (x/5) = 6/1
=> 350 - x/5 = 6x/5
=> 7x/5 = 350 => x = 250

=> Untagged mammals = (630-250) - (350 -250/5) = 80 => B
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For this particular question, the number of animals are 630 & only has birds & mammals in the group

5 out of 9 animals are tagged, which means (5/9)*630=350 tagged & by default 630-350=280 untagged

Out of the tagged animals, mammals to birds ratio is 6:1 which means 300 tagged mammals & 50 tagged birds

1/5 of the total birds are tagged so the ratio of tagged to untagged birds would be 1:4(Tagged/(Tagged+Untagged)=1:5)

So the number of untagged birds would be 50/Untagged=1/4, Untagged birds=200. Hence the number of untagged mammals would be untagged animals-untagged birds = 280-200=80

Hence the answer to this question is option (B) 80
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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


350= tagged animals=7x. Thus 300 mammals are tagged and 50 birds are taaged and since tagged birds= 1/5th of total birds hence total birds= 250. Thus untagged mammamls=630-250-300=80

Ans B
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