In the 1960s, surveys of Florida's alligator population indicated that

You have to be careful not to overthink an answer choice and imagine things that aren't there -- we aren't told that golf course access changed at all, or that people may have filed spurious reports.

It's possible that alligator sightings that "occurred at times at which few people were present" are less reliable than sightings where lots of people are present. If that is true then (E) might weaken the argument slightly -- but it's pretty tenuous.

However, the question asks us to find the answer choice that most seriously weakens the argument. To do this, take another look at (A):

If the human population increased significantly, then it's likely that at least some of these sightings occurred because there are more people around to see the alligators. There don't need to be significantly more alligators -- each alligator might have been seen multiple times because there were lots more people around to see them.

(E) might weaken the argument a little, but (A) blasts a gaping hole in the author's evidence. So, (A) more seriously weakens the argument.

I hope that helps!

I'm probably repeating things already posted in this thread, but I haven't read many replies. If an argument read "reports of Adélie penguins in Antarctica increased dramatically between 1800 and 1990, so the Adélie penguin population in Antarctica must have increased dramatically over that period", that argument would very clearly be weakened if we learned "humans first set foot on Antarctica in 1820 or 1821, and in 1990 a few thousand researchers were stationed in Antarctica". When the human population is low (or, as in this example, zero), you won't get many reports regardless of penguin population. When the human population is very high, you may get a lot of reports even about a small population, because every member of that small population might be reported (and some might be reported multiple times).

When we learn here that alligator reports increased, there are at least two competing explanations: maybe there are more alligators to report, or maybe there are more people to make reports. Answer A is a perfect answer here because it suggests an alternate explanation for the facts reported in the stem. And here I'm even ignoring other implications of A (e.g. increased human population might have destroyed natural alligator habitat, and might have led a small population of alligators to migrate to human-populated areas). I'm not sure what's tempting about E; all E suggests to me is that alligators are afraid of people. I suppose if you think this "dramatic increase" in alligator reports was, because the alligators were witnessed only by one or two people, fuelled almost entirely by erroneous reports, then E is a good answer, but that seems awfully tenuous to me.

And to maheswariviresh's concern about whether the OA to some official questions might sometimes be 'wrong': I've seen several thousand official questions (probably more than 10,000) in the many years I've been working in the GMAT field. In that time I've found exactly one official Quant question that had the wrong answer (a Statistics DS question where they neglected to consider the possibility that elements in a set might be negative). On rare occasions, I've found Verbal questions where I think two answers are justifiable, and there is a subtle difference between them that would make one preferable to the other. I've never found an official Verbal question where I'd consider the OA to be wrong, however. That makes official Verbal questions very different from prep company Verbal questions; the OA to prep co Verbal questions seems to me to be wrong about a quarter of the time, judging from the questions I read on this forum (I've very often posted replies to CR questions here pointing out issues with prep company OAs).

It's probable many test takers don't appreciate the extraordinary lengths GMAC goes to in order to ensure the quality of each test question that appears on the GMAT. Every test question undergoes an extensive editorial process, but question development doesn't stop there. Then each question is used as a purely diagnostic question on actual tests, and the response data is analyzed. If a question had an incorrect OA, they would discover it at that stage: the data would reveal that high-level test takers were mostly getting the question wrong. That can never happen with a real GMAT question, so they'd need to revisit the question, correct the issue, and use the revised version again as a diagnostic question, and only if the question had normal response patterns could they consider using it as an actual test question that counted.

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A tricky one!

A. The human population of Florida increased significantly during the 1990s.
This could probably be the reason for the increased sighting of alligators. Let’s look at the other options to see if we have a contender.

B. The hunting restrictions applied to commercial as well as private hunters.

Very much irrelevant. Was there any difference in the hunting restriction in the given period? Not sure. Eliminate.

C. The number of sightings of alligators in lakes and swamps increased greatly in Florida during the 1990s.
Only supports the conclusion that the alligator population in Florida during the 1990s increased. Eliminate.

D. Throughout the 1990s, selling alligator products was more strictly regulated than hunting was.
Irrelevant. Eliminate.


E. Most of the sightings of alligators on golf courses and lawns in the 1990s occurred at times at which few people were present on those golf courses and lawns.

Does that mean people were lying and the sightings were fake? Assumptions like these could often lead us to wrong answers. Eliminate.

Option A says that the human population of Florida increased significantly during the 1990s- More people- more sightings of alligators.
This tells us that the population of alligators has not increased but the sightings of alligators have increased because there has been an increase in the human population of Florida. Weakens the argument. Option A is correct.

Vishnupriya
GMAT Verbal SME

A. The human population of Florida increased significantly during the 1990s.- Hold. If the human population has increased than number of reportings might have increased(Alternative explanation)
B. The hunting restrictions applied to commercial as well as private hunters.- So what.....(do nothing to our argument)
C. The number of sightings of alligators in lakes and swamps increased greatly in Florida during the 1990s.(Strengthens the argument)
D. Throughout the 1990s, selling alligator products was more strictly regulated than hunting was.(Irrelevant)
E. Most of the sightings of alligators on golf courses and lawns in the 1990s occurred at times at which few people were present on those golf courses and lawns- too general statement. Neither strengthens nor weakens the argument

In the 1960s, surveys of Florida's alligator population indicated that the population was dwindling rapidly. Hunting alligators was banned. By the early 1990s, the alligator population had recovered, and restricted hunting was allowed. Over the course of the 1990s, reports of alligators appearing on golf courses and lawns increased dramatically. Therefore, in spite of whatever alligator hunting went on, the alligator population must have increased significantly over the decade of the 1990s.

Which of the following, if true, most seriously weakens the argument?

A. The human population of Florida increased significantly during the 1990s.
B. The hunting restrictions applied to commercial as well as private hunters.
C. The number of sightings of alligators in lakes and swamps increased greatly in Florida during the 1990s.
D. Throughout the 1990s, selling alligator products was more strictly regulated than hunting was.
E. Most of the sightings of alligators on golf courses and lawns in the 1990s occurred at times at which few people were present on those golf courses and lawns.

Hello guys!
I hope my explanation suffices your understanding!

Initially, I eliminated A, but understood that it was a trap.
Eliminate B as it is irrelevant.
Eliminate C as it is out of scope.
Option D is also a trap as it indirectly tells you that not selling the products would lead to a hold in the hunting. But it does not fulfil our purpose.
Option E is specific to a scenario and does not look at it on a whole.

Option A clearly weakens the statement as the human population saw a surge and it led to such a scenario.

Official Answer:- Option A


Thank you!

Regards,
Raunak Damle!

Hi experts,

I pre-thought of two scenarios in which the population of alligators need not have increased: 1) What if restrictions limiting the access of alligators to golf courses were eased? 2) What if people started reported spurious cases?

I believe option E is along the lines of (2). Most of the times if there were only one or two persons then it could be that these reports were 'fake'. How do I eliminate this answer choice?

Sighting of alligators is quite a rare event and even if the population increases significantly one cannot expect the cases to 'dramatically' increase

Don't know if this is good enough since two of the great experts in the forum have already replied.

In the 1960s, surveys of Florida's alligator population indicated that the population was dwindling rapidly. Hunting alligators was banned. By the early 1990s, the alligator population had recovered, and restricted hunting was allowed. Over the course of the 1990s, reports of alligators appearing on golf courses and lawns increased dramatically. Therefore, in spite of whatever alligator hunting went on, the alligator population must have increased significantly over the decade of the 1990s.

Which of the following, if true, most seriously weakens the argument?

Crux of the argument: Surveys in 1960s indicated dwindling alligator problems thus hunting was banned. In early 1990s the alligators populations increased and hunting with restrictions was allowed. But in the 1990s the human-alligator encounters increased as more and alligators were reported appearing on golf courses and lawns. Author concludes that, although alligator hunting was there, the population of alligators kept increased.

Here, author basically theorizes that witnessing alligators in people's lawns and golf courses is sign of increase in alligator population. So, there's a casual relationship between humans and alligators as author sees it. Strengthener would be something that supports author's reasoning. But the argument can be weakened in two ways:
1. Something else caused/led those alligators to go to people's lawns and golf courses. May be they had a gold rush moment and wanted to join exclusive golf clubs
2. Not alligators but people entered the alligators' territories. This has tow sub-cases btw
- Alligators population decreased
- Alligators population remained at same level at it was in early 1990s.

At this point it would look easy to just glance at the right answer but just check other options before looking at the right one.

A. The human population of Florida increased significantly during the 1990s. - CORRECT. This looks neutral to initially, if someone has not figured out yet what is the possible relationship between humans and alligators. From a causality point authors says seeing alligators in people's lawns and golf clubs is a signal that their population has increased i.e. X ----> Y but its the other way round Y ----> X as suggested in this option. A Venn diagram concept may help us here to understand. The common part of the two circles is the golf course and lawns. Either alligators increased that area(strengthener) or the humans increased it(weakener)[Though subconsciously i feel this is the worst example/concept application i have ever thought ]

B. The hunting restrictions applied to commercial as well as private hunters. - WRONG. So what if it did, it doesn't impact the conclusion. There's no relationship here neither suggested.

C. The number of sightings of alligators in lakes and swamps increased greatly in Florida during the 1990s. - WRONG. So the expanse of alligators sightings increases. Wow it strengthens the argument which is opposite to what we are looking for.

D. Throughout the 1990s, selling alligator products was more strictly regulated than hunting was. - WRONG. More the products, more the hunting. Here the situation is restricted hunting ---> regulated products. Again strengthens the argument.

E. Most of the sightings of alligators on golf courses and lawns in the 1990s occurred at times at which few people were present on those golf courses and lawns. - WRONG. This is the closest to being a correct answer. But if people are not present on those golf courses and lawns, are the alligators not there. No, this is not the case alligators are still there - either with increased or decreased population. Its a neutral case as far as i see.

A short note: Initially, I fell for the contrast brought by the author to solidify his/her argument. I almost thought that because author in his/her conclusion uses "in spite of whatever alligator hunting went on" to stress upon the hunting part, hunting was without restrictions. Many of us might do so but its not - hunting's still restricted.

Also, had even one of the pre-thinking points of jayarora been there in the five choices, the questions would have been more difficult since it would have fit our point 1 of weakener as above.

IMO Answer A.

I went down a similar pre-thinking route as jayarora and ended up marking E. My memory of another official CR question from OG2020 - https://gmatclub.com/forum/farmer-sever ... 94365.html - might as well have played a role in my marking E.

MentorTutoring
Regarding the part I highlighted in red, what's the fundamental difference between the premises of this CR question and the one I cited above, in terms of whether or not to accept it as truth and not doubt those people who claimed/reported the respective sightings?

Hello, Debo1988. I understand the apparent similarity between the question you linked to and this one. The difference, however, lies in the presentation, the qualifiers used to outline the situation. In that question, we get several people who reported sightings, whereas here, we see that reports of alligator sightings increased dramatically. I would like to point out that in that other question, we are told explicitly that there is no reason for the people who reported seeing a mountain lion to have deliberately concocted a false report (my italics). The conclusion is also different from the one to this question. The farmer calls for local wildlife managers... to urgently address the mountain lion's presence. Since several in that question could mean two or three, and given the other answer choices that do not seriously weaken the farmer's conclusion--answers that are either irrelevant or loosely tied to the argument, the process of elimination leads to the correct answer there. In this question, the argument is that the number of alligators has increased significantly, and regardless of when most sightings occurred, that still leaves room for other types of sightings, those in which many people were present. If, for instance, there were 1,000 sightings, and 501 occurred at times at which few people were present, then what about the other 499? Or, to be fair, if we are basing this conclusion on 3 sightings, when there had been just 1 before--a 200 percent increase!--if two of those three, or most of those sightings occurred at times at which few people were present, that still leaves that third instance, and a lot of people could have seen an alligator. Whatever the case may be, whichever numbers you want to use, choice (E) does not affect the argument in the same way, logically, as (A), for reasons better explained earlier.

I hope that helps clear your doubt. Rather than memorize an approach to a certain CR question, it will likely prove more useful to focus on exactly what information is provided in a given passage and then see what you have to work with in the answer choices. I know it is tough--CR used to be my worst area. But with a lot of practice, reading, and listening (if you prefer to watch dedicated YouTube videos), you can get the upper hand on most CR questions.

Good luck with your studies.

- Andrew

Although this quite old, to me answer A has some issues:
if the population during 1990 grows usually the increase comes from babies so 1989 has an increase of 1% lets say the usual rate and 1990 50% -> that 50% is reflected in babies for some reason babies will not go on golf courts and will certainly never report stuff to authorities.

Hello, alexjsfk. Now you are conjuring up babies—perhaps facetiously—to qualify the growth in the human population of Florida, but, of course, a growth in population can occur for any of a number of reasons, and Florida has a reputation for attracting both the elderly and carefree spring breakers. Maybe the latter flooded the links in the 90s in hopes of engaging in drunken alligator wrestling? We can only speculate...

- Andrew

VeritasPrepHailey mam Please explain this question and process of elimination
I am still unable to link how increase in human population in 1990s can show that there is no increase in alligator's population

Sure thing vasuca10!

(As a Floridian, this question's representation of Florida as "hunting, alligators, and golf courses" definitely gave me a laugh! )

So, if we start with the question stem, we can see that we're looking to weaken the argument. In this case, we're looking to weaken the connection between the fact that "reports of alligators appearing on golf courses and lawns increased dramatically" and the conclusion that "in spite of whatever alligator hunting went on, the alligator population must have increased significantly over the decade of the 1990s."



Basically, we want something that tells us that it might not make sense to use the evidence of an increase in alligator reports to conclude that the alligator population must have increased significantly. I'd point out, this is a bit different from what you verbalized. We aren't necessarily looking for something that definitively tells us the alligator population did not or could not have increased, we just need something that breaks up the connection between evidence and conclusion and presents a case where it might not make sense to use the increase in reports to conclude that the alligator population has increased. Let's take a look at the answers!


A. The human population of Florida increased significantly during the 1990s. <- Hmmm... we were told *reports* of alligator sightings have increased. Does that necessarily mean that the population of alligators has increased? The argument seems to conflate increased reports with increased population, but that doesn't have to be true. If there are more people around to see and report alligators, it wouldn't necessarily make sense to use the change in sightings to draw conclusions about the population. (this is a common gap in reasoning we want to be on the lookout for in GMAT CR!)

B. The hunting restrictions applied to commercial as well as private hunters. <- Who the hunting restrictions applied to doesn't really matter to us here. This does nothing to tell us why it might not make sense to use the given evidence to draw the cited conclusion.

C. The number of sightings of alligators in lakes and swamps increased greatly in Florida during the 1990s. <- Providing additional sources of alligator sightings definitely doesn't weaken the connection between evidence and conclusion. This just provides further evidence that more alligator sightings are taking place. We need something that specifically breaks up the connection between sightings and population.

D. Throughout the 1990s, selling alligator products was more strictly regulated than hunting was. <- ....Okay, so what? Even if people are more limited in their ability to sell gator jerky and gator-skin boots, this does nothing to break up the connection between the sightings reported and population.

E. Most of the sightings of alligators on golf courses and lawns in the 1990s occurred at times at which few people were present on those golf courses and lawns. <- Well, we only need one person around to "see something and say something" about the alligators, so this definitely doesn't tell us that the reports cannot be used to substantiate an increase in population. If anything, if few people are present when the sightings occur *and* the reports of sightings increase, it would be less likely that we have repeat sightings where many people make the same report. So, definitely not a weakener here. Keep in mind, we aren't trying to weaken the evidence... it's already been presented as fact. We have already been told that sightings increased during this time. We want something that tells us increased sightings does not necessarily = increased alligator population.

So, if we get to the core of the argument, we're looking for something that addresses how *despite* the apparent evidence, the conclusion might be false. If the increase in reports is driven by the increase in people around to make reports, rather than by an increase in alligator population, it would no longer make sense to use data concerning reports to draw conclusions about the alligator population. So, (A) is our correct answer!

(Now, while I generally strongly urge students *not* to bring in their outside knowledge/bias in questions, I will say that I've seen this phenomenon firsthand! During months of heavy tourism/vacationing in Florida, reports of alligators (and other wildlife) *do* spike drastically. This spike is not because we have a spike in alligator population during specifically those months of the year, or because animals also trek down to Florida for their vacation, it's because there are abundantly more people around to observe and call in these wildlife sightings!)

It sounds like you may have run into trouble here because you were too focused on the conclusion on its own. Keep in mind, when we weaken an argument, we're looking to weaken the connection between evidence and conclusion, and we can do so by identifying the gap in reasoning between these components and asking ourselves "why might it not make sense to use this evidence to draw the given conclusion?" as we analyze our options. While there are many things that *could* expose the gap in logic between "reports" and "population," if we find the gap, it becomes easier to see which answer choice addresses this gap. Here, answer (A) does the trick, as it gives us reason to believe an increase in reports may not equate to an increase in alligator population.

I hope this helps!

I dont know if anyone has solved one CR question where they had a similar argument about some animal's sighting being reported recently and how that animal was not seen for years in that locality and the question was to weaken the argument

The correct answer choice to that question was somewhat along the lines, the people who reported the sightings were alone
This answer choice was explained by everyone in the comments as correct because there was no one to corroborate to the reporting of a single person

I cant remember the question or I would have attached the link to the same
If anyone remembers that question the please share the link, please do

Such opposing reasoning patterns baffle me because it creates an uncertainty about which train of thought to follow while answering these questions

Hello, himanshu11pathak. I believe you mean this question, which is about the purported sightings of a mountain lion. I have discussed both questions above in this thread after another member brought up the same question as you. Please refer to this earlier post. I hope that helps clarify your concerns.

Good luck with your studies.

- Andrew

What is the difference between nunber of sightings have increased which in option C and and the total population of humans has increased which is pption A.

I guess both the options are to do with sightings of alligators.So how are they different from rah other?

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Different meanings:

A. The human population of Florida increased significantly during the 1990s.
it indicates people are more now than before. Now more no. of people come across aligaotars than before. It indicates more reporting happen now than before
Before 5 alligators were reported by 10 people, now 5 alligators are reported by 100 people ( number of people increase). So it indicates that alligator population is not increased in actual.

C. The number of sightings of alligators in lakes and swamps increased greatly in Florida during the 1990s.
It indicates the number of alligators have increased in actual. When people used to go to lakes or swamps , they used to see 5 alligators but now they see 100 alligators.
(before everyone used to report there are 5 alligators, but now everyone indicates 100 alligators)

We have to find an option that WEAKEN:
the alligator population must have increased significantly over the decade of the 1990s.
( means alligator population was not increase in actual)
Thus, Option A fits in.

Hope it is clear.