According to some astronomers, Earth is struck by a

Question

According to some astronomers, Earth is struck by a meteorite large enough to cause an ice age on an average of once every 100 million years. The last such incident occurred nearly 100 million years ago, so we can expect that Earth will be struck by such a meteorite in the near future. This clearly warrants funding to determine whether there is a means to protect our planet from such meteorite strikes.

The reasoning in the argument is most subject to criticism on the grounds that the argument

(A) makes a bold prescription on the basis of evidence that establishes only a high probability for a disastrous event

(B) presumes, without providing justification, that the probability of a chance event’s occurring is not affected by whether the event has occurred during a period in which it would be expected to occur

(C) moves from evidence about the average frequency of an event to a specific prediction about when the next such event will occur

(D) fails to specify the likelihood that, if such a meteorite should strike Earth, the meteorite would indeed cause an ice age

(E) presumes, without providing justification, that some feasible means can be found to deter large meteorite strikes

vjsharma25 · Answer

I was also that much confident when I answered this,but answers always elude us.

gmat1220 · Answer

This is elusive ! I will consider B next.

gmat1220 · Answer

CR is based on one word.

Earth is struck by a
meteorite large enough to cause an ice age on an
 average   of once every 100 million years.

vivesomnium · Answer

I think the Answer should be A:
(A) makes a bold prescription on the basis of
evidence that establishes only a high
probability for a disastrous event:  The statement does use bold word- 'warrant' for his prescription based on evidence which at best indicates high probabilty based on average frequency 
(B) presumes, without providing justification, that the
probability of a chance event’s occurring is not
affected by whether the event has occurred during
a period in which it would be expected to occur the sentence doesnt do that- in fact it presumes the opposite 
(C) moves from evidence about the average
frequency of an event to a specific prediction
about when the next such event will occur Author is not very specific in his prediction. he says near future-- Though this option is pretty close 
(D) fails to specify the likelihood that, if such a
meteorite should strike Earth, the meteorite
would indeed cause an ice age  The author doesnt fail to specify that- he clearly presumes that a metorite atrike will cause ice age- that's his entire source of worry! 
(E) presumes, without providing justification, that
some feasible means can be found to deter
large meteorite strikes He doesnt- he only says that funding is warranted to find out whether any way to deter is possible or not

vjsharma25 · Answer

I rejected this option for the same reason you have cited,use of "specific",but this is the answer.

IEsailor · Answer

Initially though A but then went with C..Clear indicators are words "AVERAGE" and " Near Future "

ajaym28 · Answer

Found this solution, I hope this will help us for better understanding..
According to some astronomers, Earth is struck by a
meteorite large enough to cause an ice age on an
average of once every 100 million years. The last such
incident occurred nearly 100 million years ago: 
Conclusion: so we can expect that Earth will be struck by such a meteorite
in the near future. This clearly warrants funding to
determine whether there is a means to protect our
planet from such meteorite strikes.

Let's combine "So and Clearly.": Then some astronomers concludes that Earth will definately be struck by such a meteorite large enough to cause an ice age. Yet their conclusion is based on only average freuency of strikes without enough and specific evidence or data to prove it.

Analogy here: "Tom drinks a bottle of beer average of once a year. he drank one bottle of beer last year, so he will drink it in the future, which clearly warrants a strategy to determine whether there is a means to prevent him from drinking it."

Can you predict, based on average frequency of his dringking, that he will definately drink it in near future? Not really! Waht if he stops drinking it for some reasons!

(A) makes a bold prescription on the basis of
evidence that establishes only a high
probability for a disastrous event:
=in fact this describes the argument but not indicates falws.

(B) presumes, without providing justification, that the
probability of a chance event’s occurring is not
affected by whether the event has occurred during
a period in which it would be expected to occur
=180 degree to the argument.

(C) moves from evidence about the average
frequency of an event to a specific prediction
about when the next such event will occur
=Here the flaw goes.

(D) fails to specify the likelihood that, if such a
meteorite should strike Earth, the meteorite
would indeed cause an ice age
=stimulus says "large enough to cause"

(E) presumes, without providing justification, that
some feasible means can be found to deter
large meteorite strikes:
=Not warranted but opens possibility of determinig it.

eddyki · Answer

(C) moves from evidence about the average
frequency of an event to a specific prediction
about when the next such event will occur

-> flaw. the author predicts something, so we got a problem with the evidence.

agrasan · Answer

Found an amazing explanation by  Powerscore :

Flaw in the Reasoning—#%.  The correct answer choice is (C)

The argument has a complex structure, featuring two premises and a sub-conclusion that is then used
to support the main conclusion of the argument:

Premise:  According to some astronomers, Earth is struck by a meteorite large enough to cause an ice age on an average of once every 100 million years.

Premise:  The last such incident occurred nearly 100 million years ago,

Sub-conclusion:  so we can expect that Earth will be struck by such a meteorite in the near future.

Main Conclusion:  This clearly warrants funding to determine whether there is a means to protect our planet from such meteorite strikes.

Do the supporting statements prove the main conclusion? Again, personalise the argument—does it make sense that if the earth has been struck “on an average of once every 100 million years” that suddenly we are in imminent danger? Of course not. The problem is that historical averages are only averages, and you cannot predict that a meteorite strike is overdue or likely based on such averages. The reasoning in the argument is made even weaker when you consider the scale of time involved. 
Even if the historical pattern holds on average, a million or two million year variation would be a very small deviation compared to 100 million years, so it makes absolutely no sense to conclude that there will definitely be a meteorite strike in the “near future.” And, of course, if there is no certainty that earth will be struck in the near future, how can funding be “clearly warranted?”

Answer choice (A):  This choice was commonly selected, but there is no justification for this answer. The first section of the answer—“makes a bold prescription”—does occur in the reasoning. However, the second part—“on the basis of evidence that establishes only a high probability for a disastrous event”—does not occur because the stimulus does not establish a high probability for a disastrous event.

Of course, even if you saw the stimulus as establishing a high probability for disaster, wouldn’t that high probability of disaster actually be a good justifi cation for a “bold prescription?” Probably so, and thus it is hard to see how this choice would actually describes a fl aw even if everything described within it had occurred.

Answer choice (B):  The argument presumes precisely the opposite of this choice because the author believes that the probability of a chance event—the meteorite—is affected by whether or not it has happened recently. In the stimulus, the author makes clear that she believes that there is a greater likelihood of a meteorite strike today because there has not been a meteorite strike recently.

Furthermore, this choice describes reasoning that is often sound, as opposed to unsound, reasoning. Typically, a chance event is not affected by preceding events or whether there has been a recent occurrence of that event, and that is what is described in this answer. The reasoning in the stimulus, on the other hand, implies that for chance events, the past affects the future. Believing the stimulus is similar to a gambler believing that since he has thrown snake-eyes on average every third roll, it will keep happening every third roll. Historical averages, without some other supporting data, are prone to misrepresentation and misinterpretation, and should not be assumed to repeat.

Answer choice (C):  This is the correct answer choice. Both parts of the answer occur, and what is
described is a flaw:

..... “moves from evidence about the average frequency of an event”—this section describes the
..... ..... fact that a large meteorite strikes earth on an average of once every 100 million years.

..... “to a specific prediction about when the next such event will occur”—this section describes
..... ..... the sub-conclusion that “we can expect that Earth will be struck by such a meteorite
..... ..... in the near future.”

An average cannot be used to make a specific prediction, and therein lies the fl aw.

Answer choice (D):  This choice could be relevant to whether investing in preventing a strike makes good public policy; however, it does not address the main fl aw in the argument. Furthermore, even if the likelihood of an ice age resulting from a strike is very low, there could be other effects such as the destruction of cities that would suggest meteorite strike prevention as valuable, so the issue of ice ages is not critical.

Answer choice (E):  The argument does not make any presumption that preventing large strikes is feasible, it only suggests that we begin investigations into protecting Earth.

According to some astronomers, Earth is struck by a

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GMAT Critical Reasoning (CR) Questions

According to some astronomers, Earth is struck by a

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