Author 
Message 
TAGS:

Hide Tags

Senior Manager
Joined: 16 Feb 2011
Posts: 258

In a certain pond, 50 fish were caught, tagged, and returned [#permalink]
Show Tags
18 Aug 2011, 11:50
2
This post received KUDOS
8
This post was BOOKMARKED
Question Stats:
76% (02:06) correct
24% (01:42) wrong based on 306 sessions
HideShow timer Statistics
In a certain pond, 50 fish were caught, tagged, and returned to the pond. A few days later, 50 fish were caught again, of which 2 were found to have been tagged. If the percent of tagged fish in the second catch approximates the percent of tagged fish in the pond, what is the approximate number of fish in the pond? (A) 400 (B) 625 (C) 1,250 (D) 2,500 (E) 10,000
Official Answer and Stats are available only to registered users. Register/ Login.
Last edited by Bunuel on 24 Nov 2012, 05:04, edited 1 time in total.
Renamed the topic and edited the question.



Manager
Status: Quant 50+?
Joined: 02 Feb 2011
Posts: 107
Concentration: Strategy, Finance

Re: Fish  World Problem!! [#permalink]
Show Tags
18 Aug 2011, 11:56
DeeptiM wrote: In a certain pond, 50 fish were caught, tagged, and returned to the pond. A few days later, 50 fish were caught again, of which 2 were found to have been tagged. If the percent of tagged fish in the second catch approximates the percent of tagged fish in the pond, what is the approximate number of fish in the pond? (A) 400 (B) 625 (C) 1,250 (D) 2,500 (E) 10,000 2/50 recaught means that 50 fish represents 1/25th of all fish in the pond. 50*25 = 1250, C



Director
Status: No dream is too large, no dreamer is too small
Joined: 14 Jul 2010
Posts: 633

Re: Fish  World Problem!! [#permalink]
Show Tags
18 Aug 2011, 12:57
2
This post was BOOKMARKED



Director
Status: Gonna rock this time!!!
Joined: 22 Jul 2012
Posts: 520
Location: India
GMAT 1: 640 Q43 V34 GMAT 2: 630 Q47 V29
WE: Information Technology (Computer Software)

Re: Fish  World Problem!! [#permalink]
Show Tags
23 Nov 2012, 23:38
so, x * 4% = 50This is how I solved too.. This works but I dont think this is right... 4% is actually equal to percent of tagged fish in the pond.. Could somebody please confirm if this is right?
_________________
hope is a good thing, maybe the best of things. And no good thing ever dies.
Who says you need a 700 ?Check this out : http://gmatclub.com/forum/whosaysyouneeda149706.html#p1201595
My GMAT Journey : http://gmatclub.com/forum/endofmygmatjourney149328.html#p1197992



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 7440
Location: Pune, India

Re: Fish  World Problem!! [#permalink]
Show Tags
24 Nov 2012, 03:28
2
This post received KUDOS
Expert's post
2
This post was BOOKMARKED
Sachin9 wrote: so, x * 4% = 50
This is how I solved too.. This works but I dont think this is right... 4% is actually equal to percent of tagged fish in the pond..
Could somebody please confirm if this is right? This is correct. You are assuming that the total number of fish in the pond is x 4% of x = 50 (Number of tagged fish is 4% of the total fish) You get x = 1250 So total fish in the pond = 1250
_________________
Karishma Veritas Prep  GMAT Instructor My Blog
Get started with Veritas Prep GMAT On Demand for $199
Veritas Prep Reviews



GMAT Club Legend
Joined: 09 Sep 2013
Posts: 15980

Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]
Show Tags
09 Dec 2013, 17:48
Hello from the GMAT Club BumpBot! Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up  doing my job. I think you may find it valuable (esp those replies with Kudos). Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources



GMAT Club Legend
Joined: 09 Sep 2013
Posts: 15980

Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]
Show Tags
25 Mar 2015, 10:15
Hello from the GMAT Club BumpBot! Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up  doing my job. I think you may find it valuable (esp those replies with Kudos). Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources



Intern
Joined: 17 Aug 2015
Posts: 5

In a certain pond, 50 fish were caught, tagged, and returned [#permalink]
Show Tags
01 Oct 2015, 12:35
VeritasPrepKarishma wrote: Sachin9 wrote: so, x * 4% = 50
This is how I solved too.. This works but I dont think this is right... 4% is actually equal to percent of tagged fish in the pond..
Could somebody please confirm if this is right? This is correct. You are assuming that the total number of fish in the pond is x 4% of x = 50 (Number of tagged fish is 4% of the total fish) You get x = 1250 So total fish in the pond = 1250 Why is the total number of tagged fish 50 as opposed to 98. I got 98 by adding the number of tagged fish in the first catch and the number of tagged fish in the second catch. > 50+48 = 98



EMPOWERgmat Instructor
Status: GMAT Assassin/CoFounder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 9271
Location: United States (CA)
GRE 1: 340 Q170 V170

Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]
Show Tags
01 Oct 2015, 16:28
1
This post received KUDOS
Expert's post
2
This post was BOOKMARKED
HI tinnyshenoy, This prompt is about ratios (and in the broader sense, it's an example of 'representative sampling'). To start, we're told that 50 fish are caught, tagged and returned to the pond. There are now an UNKNOWN number of total fish in the pond, but 50 of them are 'tagged.' Later on, 50 fish are again caught, but 2 of them are ALREADY TAGGED. We're told that the percent of fish IN THIS GROUP that are tagged is approximately = the TOTAL percent of ALL fish that are tagged....With this information, we can set up a ratio... 2/50 = ratio of tagged fish in this sample 50/X = ratio of tagged fish in the pond 2/50 = 50/X Now we can crossmultiply and solve for X... 2X = 2500 X = 1250 Final Answer: GMAT assassins aren't born, they're made, Rich
_________________
760+: Learn What GMAT Assassins Do to Score at the Highest Levels Contact Rich at: Rich.C@empowergmat.com
Rich Cohen
CoFounder & GMAT Assassin
***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 7440
Location: Pune, India

Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]
Show Tags
01 Oct 2015, 19:49
tinnyshenoy wrote: VeritasPrepKarishma wrote: Sachin9 wrote: so, x * 4% = 50
This is how I solved too.. This works but I dont think this is right... 4% is actually equal to percent of tagged fish in the pond..
Could somebody please confirm if this is right? This is correct. You are assuming that the total number of fish in the pond is x 4% of x = 50 (Number of tagged fish is 4% of the total fish) You get x = 1250 So total fish in the pond = 1250 Why is the total number of tagged fish 50 as opposed to 98. I got 98 by adding the number of tagged fish in the first catch and the number of tagged fish in the second catch. > 50+48 = 98 Very simply  the 50 fish caught in the second catch were not tagged. They were just caught and it was observed that 2 of them are tagged. The leftover 48 were not tagged. The second catch was only to find the approximate percentage of tagged fish in the pond (a technique called sampling). For example: In a large population, it is difficult to find the number of people with a certain trait, say red hair. So you pick up 100 people at random (unbiased selection) and see the number of people who have red hair. Say, 12 have red hair. So you can generalise that approximately 12% of the whole population has red hair. Here, since counting the number of total fish in the pond is hard, they tagged 50 and let them disperse evenly in the population. Then they caught 50 and found 2 to be tagged. So approximately 4% of the fish were tagged. So 50 is 4% of the entire fish population of the pond. Note that the method uses huge approximation because of the small sample number. If 1 more tagged fish were caught among the 50, it would change the approximated fish population number by a huge amount. But they have given us that "the percent of tagged fish in the second catch approximates the percent of tagged fish in the pond" so we can make this approximation.
_________________
Karishma Veritas Prep  GMAT Instructor My Blog
Get started with Veritas Prep GMAT On Demand for $199
Veritas Prep Reviews



Manager
Joined: 23 Dec 2014
Posts: 51

Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]
Show Tags
27 Mar 2016, 12:49
Is it a 600 level question or more?



Intern
Joined: 27 Oct 2016
Posts: 3
Location: Argentina
Concentration: General Management, Operations
WE: Engineering (Energy and Utilities)

Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]
Show Tags
21 Feb 2017, 02:30
Hi can you help me with this problem? The last part of the problem It is not clear for me. I don't know if I have to use 50 fish or 48 fish still in the pond
 2 fish tagged / 50 in the second catch  48 fish are still in the pond
So the equation is: 48 fish tagged in the pond/Tot in the pond = 2 fish tagged out/50 fish catched Tot in the pond = 48*2/50 = 1200 (aprox. 1250) > answer is C



Manager
Joined: 19 Aug 2016
Posts: 88
Location: India
GPA: 3.82

Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]
Show Tags
30 Apr 2017, 11:41
Sachin9 wrote: so, x * 4% = 50
This is how I solved too.. This works but I dont think this is right... 4% is actually equal to percent of tagged fish in the pond..
Could somebody please confirm if this is right? Hi, Although solution has already been provided for this. here is my 2 cent. I think when they say that the percent of tagged fish caught the second time represents the percent of tagged fish in the pond, they are talking about the first 50 that were tagged and left in the pond and not the 50 caught the second time. Thus, the first 50 tagged fishes are 4% of the entire fish in the pond. Hope this is clear.
_________________
Consider giving me Kudos if you find my posts useful, challenging and helpful!



Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 1158
Location: United States (CA)

Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]
Show Tags
06 May 2017, 17:28
DeeptiM wrote: In a certain pond, 50 fish were caught, tagged, and returned to the pond. A few days later, 50 fish were caught again, of which 2 were found to have been tagged. If the percent of tagged fish in the second catch approximates the percent of tagged fish in the pond, what is the approximate number of fish in the pond?
(A) 400 (B) 625 (C) 1,250 (D) 2,500 (E) 10,000 We are given that 50 fish were caught, tagged, and returned to the pond, and that a few days later, 50 fish were caught again, of which 2 were tagged. Thus, the percentage of tagged fish is 2/50 = 1/25 = 4%. Since the the percentage of tagged fish in the second catch approximates the percentage of tagged fish in the pond, the approximate number of fish in the pond is: 0.04(total fish) = 50 total fish = 50/0.04 = 5000/4 = 1250 Answer: C
_________________
Scott WoodburyStewart
Founder and CEO
GMAT Quant SelfStudy Course
500+ lessons 3000+ practice problems 800+ HD solutions




Re: In a certain pond, 50 fish were caught, tagged, and returned
[#permalink]
06 May 2017, 17:28








Similar topics 
Author 
Replies 
Last post 
Similar Topics:


2


In a forest 150 deer were caught, tagged with electronic markers, then

Bunuel 
2 
01 Aug 2016, 09:19 

17


In a certain pond, 50 fish were caught, tagged, and returned

Bunuel 
10 
29 Jul 2016, 12:08 

6


R campers fished for 3 hours. If m of the campers caught...

jlgdr 
3 
21 Jan 2016, 06:27 

1


In a forest 150 deer were caught, tagged with electronic mar

Asifpirlo 
2 
19 Jan 2015, 00:56 

4


In a certain pond, 50 fish were caught, tagged, and returned to the

Madelaine88 
6 
11 Jun 2016, 00:39 



