doubt CR 2

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doubt CR 2

by aditya8062 » Thu Dec 04, 2014 6:03 am
Iridium, a hard, whitish metal similar to platinum, is extremely rare on Earth. Extremely high concentrations of iridium on Earth result
from only two scenarios: massive volcanic eruptions that release iridium from deep within the Earth and meteorites that shower down on Earth from space. When scientists found concentrations of iridium 30 times higher than normal in rock stratum from 65 million years
ago, they concluded that a massive meteor or comet hit the Earth and caused the massive extinction of the dinosaurs.

Which of the following, if true, most strongly supports the scientist's conclusion?

A. Volcanoes massive enough to generate high concentrations of iridium are very rare.
B. Massive volcanic eruptions occurred frequently 80 million years ago.
C. Most scientists support the hypothesis that a cosmic impact wiped out the dinosaurs.
D. The massive extinction that occurred 70 million years ago killed not only the dinosaurs but also 70 percent of all life on Earth.
E. A comet struck the earth some 120 million years ago, but no widespread extinction occurred.

my concern: i selected A in this question.if we take A as correct then out of the 2 theories mentioned only "meteorites theory" seems to have occurred,thereby implying that the high concentration must have occurred as hypothesized by the scientists and hence we can conclude that a massive meteor or comet hit the Earth and caused the massive extinction of the dinosaurs.

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by MartyMurray » Thu Dec 04, 2014 9:05 am
This question does not seem that tight.

They seem to be implying that B is the right answer because massive volcanic eruptions were common before the mass extinction, so something else must have caused it. The thing is, we are looking at 15 million years between those massive eruptions and the formation of the rock strata. That makes the connection between the eruptions and the situation 65 million years ago difficult to assess at best.

Regarding answer A, really that is irrelevant. Incidents of comets hitting the earth are rare also, if you think about it. So rarity of occurrence is not an indication one way or the other.

Still, the question is not tight, and so your choosing any answer that seems half logical is not surprising.

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by mbawisdom » Sun Dec 21, 2014 8:58 am
I think (A) supports the proposition the most out of the possible answers.

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by [email protected] » Mon Dec 22, 2014 7:18 pm
Hi aditya8062,

What is the source of this question? I only ask because it doesn't "feel" like an official GMAT question. Since the prompt focuses on timeline-based data, we're expected to infer a number of things involving the timeline that aren't really inferable. I wouldn't expect to see a prompt phrased this way on Test Day.

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by aditya8062 » Mon Dec 22, 2014 7:41 pm
hi Rich
this question is from LSAT question papers there are books which publish old LSAT questions . i think it is from year 2002,though not sure about the year. i will attach the pdf of the book if possible

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by [email protected] » Mon Dec 22, 2014 9:00 pm
Hi aditya8062,

I know that there's something of a debate about this issue, but I've never been a fan of using LSAT practice questions to prepare for the GMAT. Beyond the obvious reason (it's a different Test written by different people), LSAT LR includes variations that GMAT CR does not, includes question types and wrong answer types that the GMAT does not, does not offer question difficulty in the same ratio as the Official GMAT, etc. There are plenty of sources for GMAT practice materials, so unless you're planning on taking the LSAT, I'd suggest that you focus on GMAT sources and stop spending your time and energy on LSAT material.

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by aditya8062 » Mon Dec 22, 2014 10:08 pm
i agree with you