BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Fractions

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Junior | Next Rank: 30 Posts
Posts: 12
Joined: Fri May 14, 2010 12:27 am
Thanked: 1 times

Fractions

by kannans3 » Fri May 20, 2011 7:21 am
Source: OG

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 two 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) 1250
(D) 2500
(E) 10000
Top
Source: — Problem Solving |
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Fri May 20, 2011 7:55 am
kannans3 wrote:Source: OG

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 two 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) 1250
(D) 2500
(E) 10000
In the second catch, 2/50 = 4/100 = 4% of the caught fish were found to have been tagged.
Since the percent of tagged fish in the second catch approximates the percent of tagged fish in the pond, approximately 4% of all the fish have been tagged.
Total tagged = 50.
Thus, 50 = 4% of the fish in the pond.
Now look at the answer choices. 4% of the correct answer choice must be 50.

Answer choice C: 1250
(.04)*1250 = 50.

The correct answer is C.

The other option is to solve algebraically:
50 = .04x
x = 50/(.04) = 5000/4 = 1250.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
Legendary Member
Posts: 641
Joined: Tue Feb 14, 2012 3:52 pm
Thanked: 11 times
Followed by:8 members

by gmattesttaker2 » Sun Mar 31, 2013 11:05 am
GMATGuruNY wrote:
kannans3 wrote:Source: OG

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 two 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) 1250
(D) 2500
(E) 10000
In the second catch, 2/50 = 4/100 = 4% of the caught fish were found to have been tagged.
Since the percent of tagged fish in the second catch approximates the percent of tagged fish in the pond, approximately 4% of all the fish have been tagged.
Total tagged = 50.
Thus, 50 = 4% of the fish in the pond.
Now look at the answer choices. 4% of the correct answer choice must be 50.

Answer choice C: 1250
(.04)*1250 = 50.

The correct answer is C.

The other option is to solve algebraically:
50 = .04x
x = 50/(.04) = 5000/4 = 1250.

Hello,

I was able to follow till where it says:

Thus, 50 = 4% of the fish in the pond.

I was getting confused here since the question says "the percent of fish in the second catch (i.e. 4%) approximates the percent of tagged fish in the pond". I was just thinking how 50 is the percent of tagged fish in the pond? Maybe should the question be saying "the percent of fish in the second catch (i.e. 4%) approximates the number of tagged fish in the pond (i.e. 50)?". Again, this was just a thought. Thanks for your help.

Best Regards,
Sri
Top

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 511
Joined: Wed Aug 11, 2010 9:47 am
Location: Delhi, India
Thanked: 344 times
Followed by:86 members

by Anju@Gurome » Sun Mar 31, 2013 5:20 pm
kannans3 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 two 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?
Let us assume there are N fishes in the pond.
Hence, percentage of tagged fish in the pond = (50/N)*100

Percentage of tagged fish in the second catch = (2/50)*100
Now, percentage of tagged fish in the second catch approximates the percentage of tagged fish in the pond.
So, (2/50)*100 ≈ (50/N)*100
--> N = 50*50/2 = 1250

The correct answer is C.
Anju Agarwal
Quant Expert, Gurome

Backup Methods : General guide on plugging, estimation etc.
Wavy Curve Method : Solving complex inequalities in a matter of seconds.

§ GMAT with Gurome § Admissions with Gurome § Career Advising with Gurome §
Top
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Mon Apr 01, 2013 4:03 am
gmattesttaker2 wrote:
GMATGuruNY wrote:
kannans3 wrote:Source: OG

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 two 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) 1250
(D) 2500
(E) 10000
In the second catch, 2/50 = 4/100 = 4% of the caught fish were found to have been tagged.
Since the percent of tagged fish in the second catch approximates the percent of tagged fish in the pond, approximately 4% of all the fish have been tagged.
Total tagged = 50.
Thus, 50 = 4% of the fish in the pond.
Now look at the answer choices. 4% of the correct answer choice must be 50.

Answer choice C: 1250
(.04)*1250 = 50.

The correct answer is C.

The other option is to solve algebraically:
50 = .04x
x = 50/(.04) = 5000/4 = 1250.

Hello,

I was able to follow till where it says:

Thus, 50 = 4% of the fish in the pond.

I was getting confused here since the question says "the percent of fish in the second catch (i.e. 4%) approximates the percent of tagged fish in the pond". I was just thinking how 50 is the percent of tagged fish in the pond? Maybe should the question be saying "the percent of fish in the second catch (i.e. 4%) approximates the number of tagged fish in the pond (i.e. 50)?". Again, this was just a thought. Thanks for your help.

Best Regards,
Sri
50 fish were caught again, of which two were found to have been tagged.
This statement indicates the PROPORTION of tagged fish in the SECOND CATCH:
(tagged fish in the second catch)/(total number of fish in the second catch) = 2/50 = 1/25.

The percent of tagged fish in the second catch approximates the percent of tagged fish in the pond.
In other words:
The PROPORTION of tagged fish in the ENTIRE POND is about equal to the PROPORTION of tagged fish in the SECOND CATCH.
Thus, the proportion of tagged fish in the ENTIRE pond ≈ 1/25.

In a certain pond, 50 fish were caught, TAGGED, and returned to the pond.
Since these 50 tagged fish are about equal to 1/25 of the total number of fish in the entire pond, we get:
50 ≈ (1/25)x
x ≈ 1250.

The correct answer is C.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
Post new topic Post Reply
• Page 1 of 1