Tiger beetles are such fast runners that they can capture : GMAT Critical Reasoning (CR)
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# Tiger beetles are such fast runners that they can capture

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Tiger beetles are such fast runners that they can capture [#permalink]

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06 Dec 2012, 08:08
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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.

OA B

In the past, most children who went sledding in the winter snow in Verland used wooden sleds with runners and steering bars. Ten years ago, smooth plastic sleds became popular; they go faster than wooden sleds but are harder to steer and slow. The concern that plastic sleds are more dangerous is clearly borne out by the fact that the number of children injured while sledding was much higher last winter than it was 10 years ago.

Which of the following, if true in Verland, most seriously undermines the force of the evidence cited?

(A) A few children still use traditional wooden sleds.
(B) Very few children wear any kind of protective gear, such as helmets, while sledding.
(C) Plastic sleds can be used in a much wider variety of snow conditions than wooden sleds can.
(D) Most sledding injuries occur when a sled collides with a tree, a rock, or another sled.
(E) Because the traditional wooden sleds can carry more than one rider, an accident involving a wooden sled can result in several children being injured.

need detailed explanations. Thanks!
[Reveal] Spoiler: OA
If you have any questions
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Re: Tiger beetles are such fast runners that they can capture vi [#permalink]

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06 Dec 2012, 10:11
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nelz007 wrote:
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.

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.

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Re: Tiger beetles are such fast runners that they can capture vi [#permalink]

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06 Dec 2012, 10:27
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nelz007 wrote:
In the past, most children who went sledding in the winter snow in Verland used wooden sleds with runners and steering bars. Ten years ago, smooth plastic sleds became popular; they go faster than wooden sleds but are harder to steer and slow. The concern that plastic sleds are more dangerous is clearly borne out by the fact that the number of children injured while sledding was much higher last winter than it was 10 years ago.

Which of the following, if true in Verland, most seriously undermines the force of the evidence cited?

(A) A few children still use traditional wooden sleds.
(B) Very few children wear any kind of protective gear, such as helmets, while sledding.
(C) Plastic sleds can be used in a much wider variety of snow conditions than wooden sleds can.
(D) Most sledding injuries occur when a sled collides with a tree, a rock, or another sled.
(E) Because the traditional wooden sleds can carry more than one rider, an accident involving a wooden sled can result in several children being injured.

need detailed explanations. Thanks!

Hi nelz
this one i dont think is tough....
Injury cases involving children sledding on plastic sleds as compared to cases in which wooden sleds were used is fewer. Hence plastic sleds are dangerous is unjustified.

Though through POE only B and C are left. B is totally out of scope hence only C remains and can be the answer..

For sake of explanation i try to elaborate why i consider C as the correct answer.
(C) Plastic sleds can be used in a much wider variety of snow conditions than wooden sleds can. We have to weaken the fact that since no accident
in past can be referred in which child was sledding on plastic sleds hence plastic sled is not dangerous.
May be that plastic sleds are used in a snow condition that is not prone to accident as it can be used in different snow conditions. But this does not establishes the fact that it is not dangerous... may be until now it is never used in a condition which is prone to accident.

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Re: Tiger beetles are such fast runners that they can capture vi [#permalink]

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06 Dec 2012, 10:31
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In the past, most children who went sledding in the winter snow in Verland used wooden sleds with runners and steering bars. Ten years ago, smooth plastic sleds became popular; they go faster than wooden sleds but are harder to steer and slow. The concern that plastic sleds are more dangerous is clearly borne out by the fact that the number of children injured while sledding was much higher last winter than it was 10 years ago.

Which of the following, if true in Verland, most seriously undermines the force of the evidence cited?

(A) A few children still use traditional wooden sleds.
(B) Very few children wear any kind of protective gear, such as helmets, while sledding.
(C) Plastic sleds can be used in a much wider variety of snow conditions than wooden sleds can.
(D) Most sledding injuries occur when a sled collides with a tree, a rock, or another sled.
(E) Because the traditional wooden sleds can carry more than one rider, an accident involving a wooden sled can result in several children being injured.

We need to weaken the evidence and not conclusion.
Conclusion: The concern that plastic sleds are more dangerous.
Evidence: the number of children injured while sledding was much higher last winter than it was ten years ago.

Close between B and C
C is the only choice that weakens evidence by providing an alternative .
B dont report any time frame. Is this habit old or new? B out
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Re: Tiger beetles are such fast runners that they can capture vi [#permalink]

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06 Dec 2012, 19:13
Archit143 wrote:
nelz007 wrote:
In the past, most children who went sledding in the winter snow in Verland used wooden sleds with runners and steering bars. Ten years ago, smooth plastic sleds became popular; they go faster than wooden sleds but are harder to steer and slow. The concern that plastic sleds are more dangerous is clearly borne out by the fact that the number of children injured while sledding was much higher last winter than it was 10 years ago.

Which of the following, if true in Verland, most seriously undermines the force of the evidence cited?

(A) A few children still use traditional wooden sleds.
(B) Very few children wear any kind of protective gear, such as helmets, while sledding.
(C) Plastic sleds can be used in a much wider variety of snow conditions than wooden sleds can.
(D) Most sledding injuries occur when a sled collides with a tree, a rock, or another sled.
(E) Because the traditional wooden sleds can carry more than one rider, an accident involving a wooden sled can result in several children being injured.

need detailed explanations. Thanks!

Hi nelz
this one i dont think is tough....
Injury cases involving children sledding on plastic sleds as compared to cases in which wooden sleds were used is fewer. Hence plastic sleds are dangerous is unjustified.

Though through POE only B and C are left. B is totally out of scope hence only C remains and can be the answer..

For sake of explanation i try to elaborate why i consider C as the correct answer.
(C) Plastic sleds can be used in a much wider variety of snow conditions than wooden sleds can. We have to weaken the fact that since no accident
in past can be referred in which child was sledding on plastic sleds hence plastic sled is not dangerous.
May be that plastic sleds are used in a snow condition that is not prone to accident as it can be used in different snow conditions. But this does not establishes the fact that it is not dangerous... may be until now it is never used in a condition which is prone to accident.

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I was debating between C and E. I realized, my mistake didn't understand the argument to well. Thanks for the explanation! I've noticed though in the most seriously weakens question there are usually 2 weakener's present, have to pick the stronger one...

@Bangon thanks for pointing out the conclusion / evidence part that was a silly error on my part!
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Re: Tiger beetles are such fast runners that they can capture [#permalink]

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19 Dec 2016, 09:15
How is that you post two different questions with two different OA in the same post?

Please use search button and/or use two posts when you post multiple questions or don't add in the correct option on the timer button.
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Re: Tiger beetles are such fast runners that they can capture [#permalink]

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22 Dec 2016, 04:38
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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).

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.
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Re: Tiger beetles are such fast runners that they can capture [#permalink]

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22 Dec 2016, 15:10
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the argument basically states this -

the number of children who got injured while sledding was much higher last year --> Plastic sleds are dangerous

Immediately, we notice a problem with this argument. Absolute numbers are used to derive conclusions about ratios.

How dangerous plastic sleds are can be defined as a ratio = (Total Number of Accidents)/(Total Number of trips).

The argument uses just the numerator to draw a conclusion about the ratio (dangerousness).

A - does not weaken the argument.
If the option read something like - many children use wooden sleds and most of the children who got injured use wooden sleds - then the conclusion would be weakened.

B - incorrect.
this answer option does not change the fact that the number of accidents have increased and thus sleds are more dangerous.

this answer option suggests that the denominator (in the ratio above) has also increased. If the denominator has also increased, then the ratio need increase, even if the numerator (total number of accidents) has increased.

D - not relevant.
We are not concerned with "how an accident occurs" but rather with the actual number of accidents to gauge dangerousness of plastic sleds.

E - does not change the fact that the number of children who got injured is higher with plastic sleds than with wooden sleds. Hence, the conclusion that plastic sleds are more dangerous.
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Re: Tiger beetles are such fast runners that they can capture   [#permalink] 22 Dec 2016, 15:10
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