Tiger beetles are such fast runners that they can capture virtually an

Take a look at the argument:

Tiger beetles are very fast runners.
When running toward an insect, a tiger beetle will intermittently stop and then, a moment later, resume its attack.
There are two hypotheses presented for this behavior:

The beetles cannot maintain their pace and must pause for a moment’s rest.
While running, tiger beetles are unable to adequately process the resulting rapidly changing visual information and so quickly go blind and stop.
We need to support one of the two hypotheses and undermine the other. We don’t know which one will be supported and which will be undermined. How will we support/undermine a hypothesis?

The beetles cannot maintain their pace and must pause for a moment’s rest.

Support: Something that tells us that they do get tired. e.g. going uphill they pause more.

Undermine: Something that says that fatigue plays no role e.g. the frequency of pauses do not increase as the chase continues.

While running, tiger beetles are unable to adequately process the resulting rapidly changing visual information and so quickly go blind and stop.

Support: Something that says that they are not able to process changing visual information e.g. as speed increases, frequency of pauses increases.

Undermine: Something that says that they are able to process changing visual information e.g. it doesn’t pause on turns.

Now, we need to look at each answer choice to see which one supports one hypothesis and undermines the other. Focus on the impact each option has on our two hypotheses:

(A) When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately stops and runs away without its usual intermittent stopping.

This undermines both hypotheses. If the beetle is able to run without stopping in some situations, it means that it is not a physical ailment that makes him take pauses. He is not trying to catch his breath – so to say – nor is he adjusting his field of vision.

(B) In pursuing a swerving insect, a beetle alters its course while running and its pauses become more frequent as the chase progresses.

If the beetle alters its course while running, it is obviously processing changing visual information and changing its course accordingly while running. This undermines the hypothesis “it cannot process rapidly changing visual information”. However, if the beetle pauses more frequently as the chase progresses, it is tiring out more and more due to the long chase and, hence, is taking more frequent breaks. This supports the hypothesis, “it cannot maintain its speed and pauses for rest”.

Answer choice B strengthens one hypothesis and undermines the other. This must be the answer, but let’s check our other options, just to be sure:

(C) In pursuing a moving insect, a beetle usually responds immediately to changes in the insect’s direction, and it pauses equally frequently whether the chase is up or down an incline.

This answer choice undermines both hypotheses. If the beetle responds immediately to changes in direction, it is able to process changing visual information. In addition, if the beetle takes similar pauses going up or down, it is not the effort of running that is making it take the pauses (otherwise, going up, it would have taken more pauses since it takes more effort going up).

(D) If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit.

This answer choice might strengthen the hypothesis that the beetle is not able to respond to changing visual information since it decides whether it is giving up or not after pausing (in case there is a certain stance that tells us that it has paused), but it doesn’t actually undermine the hypothesis that the beetle pauses to rest. It is very possible that it pauses to rest, and at that time assesses the situation and decides whether it wants to continue the chase. Hence, this option doesn’t undermine either hypothesis and cannot be our answer.

(E) The faster a beetle pursues an insect fleeing directly away from it, the more frequently the beetle stops.

This answer choice strengthens both of the hypotheses. The faster the beetle runs, the more rest it would need, and the more rapidly visual information would change causing the beetle to pause. Because this option does not undermine either hypothesis, it also cannot be our answer.

Only answer choice B strengthens one hypothesis and undermines the other, therefore, our answer must be B.

Also discussed on my blog here: https://anaprep.com/critical-reasoning- ... -question/

I ll take one question at a time......
As per question we have to select an option that strengthens one and undermines the other.......Its better to take a note of both the hypothesis
1st one: Perhaps the beetles cannot maintain their pace and must pause for a moment’s rest. <<In simple terms it says it stops so as to gain more energy>>
2nd one : tiger beetles are unable to adequately process the resulting rapidly changing visual information and so quickly go blind and stop.<<it says that beetle is blind so it stops and than run>>
I think its clear that B and C are contenders.... Lets take one by one.

(C) In pursuing a moving insect, a beetle usually responds immediately to changes in the insect’s direction, and it pauses equally frequently whether the chase is up or down an incline. the portion which is highlighted is extremely important should be read and comprehend very carefully. Normally running downhill does not require too much energy its an established fact. If the beetle stops while running downhill that means it gets tired when moving down. When it is running up the incline compared to downward chase should stop for more time but as mentioned in the argument it stops for the same interval. Hence its contradictory to an established fact, Moreover it is neither strengthening the hypothesis that deals with energy nor does it weakens.
Hence weaken dump this option choice.

(B) In pursuing a swerving insect, a beetle alters its course while running and its pauses become more frequent as the chase progresses.

The bold portion weakens the fact that the beetle is blind since it alters its course while chasing and the underlined portion strengthens the fact that it stops to take rest.
Hence B is the right answer.

---------------------------------------------------------
Consider Kudos if my post helped!!!!

This is my point of view for this really hard question:

We have to chose whether the tiger beetles is following one of the two hypothesis proposed. In fact, this question is simple when you take the words that are in the text. The first hypothesis states that the TB cannot maintain their pace and pause for moments of rest. The second states that rapidly changes in visual information lead to the blindness of the TB and then the TB has to STOP.

Therefore :

A When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately stops and runs away without its usual intermittent stopping. totally irrelevant
B In pursuing a swerving insect, a beetle alters its course while running and its pauses become more frequent as the chase progresses. wrong, because the statement two STATES THAT THE TB NEEDS TO STOP. Here they are saying that TB, following the visual change still continues to follow the prey and do not stop
C In pursuing a moving insect, a beetle usually responds immediately to changes in the insect's direction, and it pauses equally frequently whether the chase is up or down an incline. CORRECT, this answer choice is saying that the statement one is correct and the second two need to be wrong while the TB do not stop
D If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit. Irrelevant
E The faster a beetle pursues an insect fleeing directly away from it, the more frequently the beetle stops. Irrelevant

Two hypothesis:
1) Pauses to rest
2) Pauses to determine the visual information

A When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately stops and runs away without its usual intermittent stopping.
1) if the beetle pauses to rest , how can it move away without pausing? - Doesn't support
2) If the beetle pauses to determine the visual information, how come the beetle goes away. It should pause and figure out the new information - Doesn't support

B In pursuing a swerving insect, a beetle alters its course while running and its pauses become more frequent as the chase progresses.
1) Pauses to rest -> The pausing should not be more frequent but constant -> Doesn't support
2) Pauses to determine the visual information. As the motion is swerving, the visual information changes quite frequently and supports the 2nd hypothesis

C In pursuing a moving insect, a beetle usually responds immediately to changes in the insect's direction, and it pauses equally frequently whether the chase is up or down an incline.
1) Pauses to rest -> Cannot pause equally frequently in both up slope and down slop -> Doesn't support
2) Pauses to determine the visual information -> "a beetle usually responds immediately to changes in the insect's direction" -> Doesn't support

D If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit.
1) Pauses to rest -> above information doesn't support
2) Pauses to determine the visual information -> Above information doesn't support

E The faster a beetle pursues an insect fleeing directly away from it, the more frequently the beetle stops.
1) pauses to rest -> faster the beetle pursues , frequently it stops -. Supports the hypothesis
2) pauses to determine the visual information -> faster it pursues -> faster the visual information changes and more frequently it stops -> Supports the hypothsis

hence B)

The answer is an easy peasy B

Explaination :- Like always, it is advisable to break the argument into premise and conclusion.
In this question there will be a minor difference because there will be two conclusions and we have to strengthen one conclusion and completely destroy the other conclusion

Lets break the argument :-
Premise 1) Beetles are fast runner
Premise 2) When chasing an insect, beetle run, stop, then run, then again stop, and then again run and so on....

Conclusion 1 ) When running fast, beetle get tired and cannot maintain the speed. So beetle rests.<=== The beetles cannot maintain their pace and must pause for a moment's rest (mentioned in the passage)
Conclusion 2) When running fast beetle gets blinds.. stops.. regain the eyeside..and runs again. <==Beetles quickly go blind and stop. (mentioned in passage)

Now lets check what answer choices agrees with one conclusion and disagrees with other conclusion

A) When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately stops and runs away without its usual intermittent stopping.
WRONG-So when beetle is chased by another insect he runs without stopping. He neither gets tired nor go blind. He runs like Usian Bolt. ==>BOTH CONCLUSIONS DESTROYED

B) In pursuing a swerving insect, a beetle alters its course while running and its pauses become more frequent as the chase progresses.
Right- when a insect swerves (changes its direction), beetle also changes its direction. meaning he can see the insect changing direction. So it means beetle does not go blind.. he can see an insect changing its path. SO SECOND CONCLUSION DESTROYED. As the chase takes longer time, beetle rest more and more.. Meaning beetle might get tired more and more and have to rest... FIRST CONCLUSION SUPPORTED.

C) In pursuing a moving insect, a beetle usually responds immediately to changes in the insect's direction, and it pauses equally frequently whether the chase is up or down an incline.
Wrong:- Beetle respond to insect's direction change meaning beetle can see ..he does not go blind..SECOND CONCLUSION DESTROYED. Beetle takes equal number of pause whenever he is running uphill (more tiresome task.. against gravity) or down (easier to run.. gravity helps) SO FIRST CONCLUSION DESTROYED. getting tired has nothing to do with stopping. There is some other reason. FIRST CONCLUSION DESTROYED. ==>BOTH CONCLUSIONS DESTROYED

D) If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit.
Wrong :-Irrelevant.. It shows that beetle is clever. He knows its no use running because he will never catch the insect. But this option talks neither about stopping, nor going blind. SO ITS A USELESS OPTION ==>BOTH CONCLUSIONS INTACT.

E) The faster a beetle pursues an insect fleeing directly away from it, the more frequently the beetle stops.
Wrong:- This option is merely a rephrasing of second premises. (Premise 2:- When chasing an insect, beetle run, stop, then run, then again stop, and then again run and so on...) It does not address the conclusions ==> BOTH CONCLUSIONS INTACT.

So we can see that only option B does what the question is asking. Saving one conclusion while destroying the other .. hence B is correct

Tiger beetles are such fast runners that they can capture virtually any nonflying insect. However, when running toward an insect, a tiger beetle will intermittently stop and then, a moment later, resume its attack. Perhaps the beetles cannot maintain their pace and must pause for a moment's rest; but an alternative hypothesis is that while running, tiger beetles are unable to adequately process the resulting rapidly changing visual information and so quickly go blind and stop.

Which of the following, if discovered in experiments using artificially moved prey insects, would support one of the two hypotheses and undermine the other?

A When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately stops and runs away without its usual intermittent stopping.
B In pursuing a swerving insect, a beetle alters its course while running and its pauses become more frequent as the chase progresses.

C In pursuing a moving insect, a beetle usually responds immediately to changes in the insect's direction, and it pauses equally frequently whether the chase is up or down an incline.
D If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit.
E The faster a beetle pursues an insect fleeing directly away from it, the more frequently the beetle stops.

While I agree that the explanation from Veritas makes sense, it is inconsistent with the explanation given in the OA. The explanation given in the OA is:

statement provides information that strengthens the second hypothesis: the swerving pursuit and the resulting continual course adjustments appear to be forcing the beetle to stop with increasing frequency to sort out the erratic visual information

Can anyone clarify?

OG explanations are not well thought out. The given answer would be correct but the explanations do have issues.

Notice what it says in the "Reasoning":
"If the frequency of stopping increases when the beetle follows a swerving insect and must constantly change its course, then the second hypothesis is strengthened."

But (B) says that the beetle changes course while running. So the frequency of stopping doesn't increase because of the swerving insect. Hence (B) actually undermines the second hypothesis.

Hi Karishma
I chose Choice B .Because its swerving insect, visual issues as mentioned. Therefore this reason is strengthened and the other weakened.
Whereas choice E undermines the visual information and supports the pace information.

Does this reasoning makes sense?

Choice (E) strengthens both the hypotheses.

(E) The faster a beetle pursues an insect fleeing directly away from it, the more frequently the beetle stops.

H1 - the beetles cannot maintain their pace and must pause for a moment's rest;
The faster it runs, the more rest it would need. Strengthens

H2 - while running, tiger beetles are unable to adequately process the resulting rapidly changing visual information and so quickly go blind and stop
The faster it runs, the more rapidly visual information would change and more it will need to pause. Strengthens

Only option (B) undermines one and strengthens the other.

It is always better to simplify the argument -
There are two hypotheses

1. they need rest
2. they go blind

We need to strengthen one and weaken the other.

Let us look at each of the answer options -
A- weakens both the hypotheses.
Suggests that the beetle is not blind(beetle immediately stops) and does not need rest (runs away without its intermittent stopping).

B - weakens hypothesis 2. (in pursuing a swerving insect, it alters its course while running)
strengthens hypothesis 1. (pauses become more frequent).

this is the correct answer.

C - weakens hypothesis 2. (responds to changes in direction immediately)
weakens hypothesis 1. (pauses are equally frequent whether up or down an incline).

D - does not have any effect on either hypothesis 1 or 2.

E - strengthens hypothesis 1.
Does not have any effect on hypothesis 2.

There appears to be some confusion about this question, in part because multiple versions of it are floating around. Apparently a different version appears in GMAT Prep at some point, with a different OA. Thanks to bb for correcting the OA in this thread.

The version posted here in this thread is the version that appears in the OG 11th ed, Diagnostic Test #25. Here is the OE that the OG gives:

(A) The hypotheses concern ongoing pursuit; since this information is not about the beetle's continuing pursuit of prey, it neither strengthens nor weakens either hypothesis.

(B) Correct. This statement provides information that strengthens the second hypothesis: the swerving pursuit and the resulting continual course adjustments appear to be forcing the beetle to stop with increasing frequency to sort out the erratic visual information.

(C) In this experiment, since neither vision nor tiredness appears to be problematic, the beetle could be stopping for other reasons; this information neither strengthens nor weakens either hypothesis.

(D) This information is irrelevant since both the hypotheses are about mid-pursuit behaviors.

(E) The correlation of frequency of stops with speed affects both hypotheses equally; the pauses could be equally due to an inability to maintain the pace or due to a need to process the visual information.

Let me know if anyone has any questions about this.

Mike

Tiger beetles are such fast runners that they can capture virtually any nonflying insect. However, when running toward an insect, a tiger beetle will intermittently stop and then, a moment later, resume its attack. Perhaps the beetles cannot maintain their pace and must pause for a moment's rest; but an alternative hypothesis is that while running, tiger beetles are unable to adequately process the resulting rapidly changing visual information and so quickly go blind and stop.

Which of the following, if discovered in experiments using artificially moved prey insects, would support one of the two hypotheses and undermine the other?

(A) When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately stops and runs away without its usual intermittent stopping. -This is out of scope. We are looking for a scenario in which the beetle chases the insect and not the other way round.
(B) In pursuing a swerving insect, a beetle alters its course while running and its pauses become more frequent as the chase progresses. -Correct. "altering of path" weakens the second hypothesis that suggests that beetles stop to adapt to the changing visual information. "frequent pauses" strengthen the first hypothesis that states that beetles stop because they get tired during the chase.
(C) In pursuing a moving insect, a beetle usually responds immediately to changes in the insect's direction, and it pauses equally frequently whether the chase is up or down an incline. -The "changing of direction" weakens the second hypothesis. The beetle pauses up/down the slope indicate that the beetle isn't stopping because it gets tired, but because of something else, since while chasing the insect on an inclined surface the beetles should stop more than while chasing the insects on a declined surface. Thus, this gives an alternate reasoning for the first hypothesis, weakening the hypothesis. Since both the options weaken both the hypothesis, this option is incorrect.
(D) If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit. -Out of scope.
(E) The faster a beetle pursues an insect fleeing directly away from it, the more frequently the beetle stops. -This option strengthens the first hypothesis, but doesn't talk about the second hypothesis.

Hello,

According to the official solution (GMAT OG - 2018, diagnostic test, q-73) option choice B is the correct answer, but option B strengthens the second hypothesis (ie. they stop intermittently to process images) and weakens the alternate hypothesis.

Why so?


Sent from my iPad using GMAT Club Forum mobile app

Hi GMATNinja

if the beetle run away non stop from prey insect, it means the beetle doesn't need to pursue the insect so change the visual information is not needed ( this approve the second hypothesis) while the beetle is run without stop means it doesn't need to take a rest( so, disapprove the first hypothesis)

am I wrong?

craveyourave


I concur. The GMAT Club Guide to OG'11 doesn't have a note explaining a problem with the question either. The OG explanation is straight up bad. While researching this question I've come across other sites that state the OG has in-house question writers but outsources the answers. In writing that I am not confirming or supporting. Some input from others would be good. Especially from GMATNinja - how often do your answers conflict with the OG? I mean that in a positive sense - how often do you need to correct the material.

soodia

I also chose A when doing the test for your reasons, but on review I believe B is a better answer.

I think the problem with A is ambiguity. Maybe it doesn't run away as far as it chases? Maybe it doesn't need visual information cause it returns the way it came. Maybe it's at a slower pace. But, to say it is out of scope seems like a cop out. Analogy: Is Steve able to lift his 20kg child to his shoulder? Steve can lift a 30kg bag of rice to his shoulder.

Heh heh, good question. Honestly, I stopped looking at the OG explanations a really, really long time ago, for all sorts of reasons. In quant, the OG explanations tend to be overly mechanical and orthodox, and they're often not the most efficient, intuitive solution. In SC, the explanations tend to be far too simplistic: "(B) is awkward" -- and whenever that happens, it's a fair bet that the original question-writers had something more specific in mind.

So yes: the explanations are generally written by contractors hired by the publisher, often years or even decades after the original questions were written. And as a result, the explanations aren't always ideal. It's rare that the explanations are objectively WRONG, but it does happen occasionally.

But I wouldn't lose too much sleep over it. Whenever you're not thrilled with an OG explanation, come on over to GMAT Club -- we have thousands of times more words than the OGs.



(A) has a couple of issues. First, the situation in (A) involves moving a prey insect closer to the beetle, and that situation is completely different than the one described in the passage. So it's arguably irrelevant. But the better argument (which I admittedly didn't mention in my original explanation) is that if the tiger beetle doesn't stop intermittently, then it undermines BOTH hypotheses. The tiger beetle apparently doesn't really get tired when it runs, and it apparently doesn't go blind, either. So (A) can't be the answer, since it doesn't support one of the hypotheses.

I hope this helps!

After going through choices
A, D and E are not answering to question in statement
Narrowing down to B and C
C only supports alternative hypothesis but not weakening the other one
whereas B weaken the alternative by showing it alters its direction and strengthening that it is tiring as stop increases as chase prolongs