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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 24 Dec 2024, 22:36
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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




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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 00:22
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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
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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 00:51
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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

 


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for the 12 Days of Christmas Competition

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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 01:03
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Ans: B
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
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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

MBTotal
T30050350
UT?=200280
Total250630

We get UT = 80
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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 01:48
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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

 


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for the 12 Days of Christmas Competition

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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.
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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 02:21
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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.
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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 02:31
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350 = tagged animals
300= tagged mammals, tagged birds =50
Total birds = 250
This untagged mammals = 630-350-200= 80

Ans b
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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 03:14
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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?

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.
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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 03:42
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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
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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 03:53
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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
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

 


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for the 12 Days of Christmas Competition

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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 04:34
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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

 


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for the 12 Days of Christmas Competition

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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 StatusMammalBirdAnimal
Tagged30050350
Untagged80200280
Total380250630

[b] is the correct answer.[/b]
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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 04:50
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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

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
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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 05:34
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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
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

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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 05:38
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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
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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 05:44
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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

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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.
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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 06:34
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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)
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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 06:50
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Quote:
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
Show more

taggednot taggedTotal
birdsb/54b/5b
mammalsm
Total350280630

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
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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 07:09
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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
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

 


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for the 12 Days of Christmas Competition

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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 07:39
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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
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

 


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for the 12 Days of Christmas Competition

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12 Days of Christmas GMAT Competition - Day 7: At a wildlife sanctuary 25 Dec 2024, 08:01
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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
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