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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?

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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

The percent of tagged fish in the second catch is 2/50*100 = 4%.

We are told that 4% approximates the percent of tagged fish in the pond. Since there are 50 tagged fish, then we have 0.04x = 50 --> x = 1,250.

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

# of fishes caught in the 2nd catch = 50 and # of fishes which are tagged = 2 so %age = 4% And after the 1st catch, the # of fish which are tagged are = 50 which is 4% of # of fishes in the pond, so total number of fishes = 25*50 = 1250 - Option C)
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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

The percent of tagged fish in the second catch is 2/50*100 = 4%.

We are told that 4% approximates the percent of tagged fish in the pond. Since there are 50 tagged fish, then we have 0.04x = 50 --> x = 1,250.

Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]

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06 Jul 2015, 09:59

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Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]

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28 Jul 2016, 07:48

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).

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

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29 Jul 2016, 11:02

Hey Bunuel i have a query in this question Here why arent we taking the number of tagged fishes as 48 as 2 fishes that were caught arent returned to the pond. we have no evidence that the two fishes were returned to the pond so (4/100)*number of fishes = 48 although no option is provided i think its answer should be 1200

Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]

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29 Jul 2016, 11:23

1

This post received KUDOS

stonecold wrote:

Hey Bunuel i have a query in this question Here why arent we taking the number of tagged fishes as 48 as 2 fishes that were caught arent returned to the pond. we have no evidence that the two fishes were returned to the pond so (4/100)*number of fishes = 48 although no option is provided i think its answer should be 1200

Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]

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29 Jul 2016, 11:28

abhimahna wrote:

stonecold wrote:

Hey Bunuel i have a query in this question Here why arent we taking the number of tagged fishes as 48 as 2 fishes that were caught arent returned to the pond. we have no evidence that the two fishes were returned to the pond so (4/100)*number of fishes = 48 although no option is provided i think its answer should be 1200

True. If one of the options would have been 1200, then this could be a concern.

But I believe GMAC people are intelligent enough to avoid such options that cause confusions.

So, since we donot have any option that matches per your assumption, we need to consider 50 tagged fishes only.

Hope it clears your query!!

Nopes bruh..! I disagree . I think we are really missing something here . Abhishek009 has stopped doing quant i guess else he would have been the first one to respond on this Lets wait for Bunuel to respond
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There are a few different ways to address the interpretational 'issue' that you're talking about:

To start, regardless of how you interpret the prompt, the question ultimately asks for the APPROXIMATE number of fish in the pond - your way of interpreting the question leads to the SAME correct answer. Thus, it doesn't really matter that you didn't get to 1250 exactly.

Second, IF the question expected you to calculate a result by 'ignoring' the 50 fish that were caught the second time, then it would have asked for the number of REMAINING fish in the pond (which the prompt did not do). By extension, you would have to question your interpretation of the wording (and possibly consider an alternative interpretation - which you seem to refuse to do). While minor interpretational 'biases' can sometimes happen in GMAT questions, the answer choices will be written so that there can only be one correct answer. If "your answer" isn't there, then you have to consider how you interpreted the given information and adjust your work accordingly.

Third, from a ratio standpoint, the 50 fish 'subgroup' that was caught the second time IS, mathematically speaking, part of the total number of fish in the pond (so you can't ignore that group when calculating the total number of fish in the pond).