Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 24 Nov 2015, 14:23

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

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

Author Message
TAGS:
Senior Manager
Joined: 15 Feb 2011
Posts: 262
Followers: 4

Kudos [?]: 74 [0], given: 9

In a certain pond, 50 fish were caught, tagged, and returned [#permalink]  18 Aug 2011, 10:50
6
This post was
BOOKMARKED
00:00

Difficulty:

25% (medium)

Question Stats:

76% (02:01) correct 24% (01:56) wrong based on 170 sessions
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
[Reveal] Spoiler: OA

Last edited by Bunuel on 24 Nov 2012, 04:04, edited 1 time in total.
Renamed the topic and edited the question.
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 6062
Location: Pune, India
Followers: 1593

Kudos [?]: 8920 [2] , given: 195

Re: Fish - World Problem!! [#permalink]  24 Nov 2012, 02:28
2
KUDOS
Expert's post
1
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 EMPOWERgmat Instructor Status: GMAT Assassin/Co-Founder Affiliations: EMPOWERgmat Joined: 19 Dec 2014 Posts: 4560 Location: United States (CA) GMAT 1: 800 Q51 V49 GRE 1: 340 Q170 V170 Followers: 192 Kudos [?]: 1269 [1] , given: 133 Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink] 01 Oct 2015, 15:28 1 This post received KUDOS Expert's post 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 cross-multiply and solve for X... 2X = 2500 X = 1250 Final Answer: [Reveal] Spoiler: C GMAT assassins aren't born, they're made, Rich _________________ Rich Cohen Rich.C@empowergmat.com EMPOWERgmat Online Course | GMAT Club Verified Reviews for EMPOWERgmat & Special Discount http://www.empowergmat.com Veritas Prep GMAT Instructor Joined: 16 Oct 2010 Posts: 6062 Location: Pune, India Followers: 1593 Kudos [?]: 8920 [1] , given: 195 Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink] 01 Oct 2015, 18:49 1 This post received KUDOS Expert's post 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
Status: Quant 50+?
Joined: 02 Feb 2011
Posts: 107
Concentration: Strategy, Finance
Schools: Tuck '16, Darden '16
Followers: 1

Kudos [?]: 26 [0], given: 22

Re: Fish - World Problem!! [#permalink]  18 Aug 2011, 10:56
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 re-caught 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: 649
Followers: 37

Kudos [?]: 486 [0], given: 39

Re: Fish - World Problem!! [#permalink]  18 Aug 2011, 11:57
1
This post was
BOOKMARKED
total fish = x
percentage of second catch = (2/50)*100 = 4%
so, x * 4% = 50
x = 1250 ans.
_________________

Collections:-
PSof OG solved by GC members: http://gmatclub.com/forum/collection-ps-with-solution-from-gmatclub-110005.html
DS of OG solved by GC members: http://gmatclub.com/forum/collection-ds-with-solution-from-gmatclub-110004.html
100 GMAT PREP Quantitative collection http://gmatclub.com/forum/gmat-prep-problem-collections-114358.html
Collections of work/rate problems with solutions http://gmatclub.com/forum/collections-of-work-rate-problem-with-solutions-118919.html
Mixture problems in a file with best solutions: http://gmatclub.com/forum/mixture-problems-with-best-and-easy-solutions-all-together-124644.html

Director
Status: Gonna rock this time!!!
Joined: 22 Jul 2012
Posts: 547
Location: India
GMAT 1: 640 Q43 V34
GMAT 2: 630 Q47 V29
WE: Information Technology (Computer Software)
Followers: 2

Kudos [?]: 45 [0], given: 562

Re: Fish - World Problem!! [#permalink]  23 Nov 2012, 22:38
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?
_________________

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/who-says-you-need-a-149706.html#p1201595

My GMAT Journey : end-of-my-gmat-journey-149328.html#p1197992

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 7249
Followers: 383

Kudos [?]: 93 [0], given: 0

Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]  09 Dec 2013, 16:48
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 Club Legend
Joined: 09 Sep 2013
Posts: 7249
Followers: 383

Kudos [?]: 93 [0], given: 0

Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]  25 Mar 2015, 09:15
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.
_________________
Intern
Joined: 17 Aug 2015
Posts: 3
Followers: 0

Kudos [?]: 0 [0], given: 1

In a certain pond, 50 fish were caught, tagged, and returned [#permalink]  01 Oct 2015, 11:35
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
In a certain pond, 50 fish were caught, tagged, and returned   [#permalink] 01 Oct 2015, 11:35
Similar topics Replies Last post
Similar
Topics:
10 In a certain pond, 50 fish were caught, tagged, and returned 5 10 Jan 2014, 06:10
4 In a certain candy store, 22% of the customers are caught sa 9 11 Oct 2013, 01:09
2 R campers fished for 3 hours. If m of the campers caught... 1 17 Sep 2013, 07:50
1 In a forest 150 deer were caught, tagged with electronic mar 2 21 Aug 2013, 16:37
10 Of the goose eggs laid at a certain pond, 2/3 hatched and 3/ 10 19 Jun 2008, 23:38
Display posts from previous: Sort by