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# When a planetary system forms, the chances that a planet

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Director
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When a planetary system forms, the chances that a planet  [#permalink]

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09 Jul 2008, 06:42
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45% (01:37) correct 55% (01:51) wrong based on 1387 sessions

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When a planetary system forms, the chances that a planet capable of supporting life will be formed are high. The chances that a large planet the size of Jupiter or Saturn will be formed, however, are low. Without Jupiter and Saturn, whose gravitational forces have prevented Earth from being frequently struck by large comets, intelligent life would never have arisen on Earth. Since planetary systems are unlikely to contain any large planets, the chances that intelligent life will emerge on a planet are, therefore, low.

Knowing which one of the following would be most useful in evaluating the argument?

(A) whether all planetary systems are formed from similar amounts of matter
(B) whether intelligent species would be likely to survive if a comet struck their planet
(C) whether large comets could be deflected by only one large planet rather than by two
(D) how high the chances are that planetary systems will contain many large comets
(E) how likely it is that planetary systems containing large planets will also contain planets the size of Earth
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Re: CR - planetary system  [#permalink]

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09 Jul 2008, 06:53
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I get D.

Premise: the chances that a planet capable of supporting life will be formed are high.

Premise: The chances that a large planet the size of Jupiter or Saturn will be formed, however, are low.

Premise: Without Jupiter and Saturn, whose gravitational forces have prevented Earth from being frequently struck by large comets, intelligent life would never have arisen on Earth.

Conclusion: Since planetary systems are unlikely to contain any large planets, the chances that intelligent life will emerge on a planet are, therefore, low.

The conclusion of the argument is based on the facts that large planets are needed to pull large comets away from the smaller planets that can support life. If there are no comets to pull away then the conclusion fails.
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Re: CR - planetary system  [#permalink]

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09 Jul 2008, 10:19
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Nice explanation gixxer1000; I gave you (+1).

After going through Premises and answer choices, I overlooked the term 'large comet' and hence ignored choice D as well. Is there any quick mechanical process to get the answer correct while somebody wades through question and still does not get answer?

OA is D.
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Re: CR - planetary system  [#permalink]

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09 Jul 2008, 11:06
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Here is my method.

Whenever you see the word argument think conclusion.

There are only 3 parts any argument.

1) Premise: This is something that is presented as fact. It may or may not be true in the real world but in the argument it is presented as though it is true and should be treated so.

ex. All dogs run faster than cats.

You may be able to find a cat that can run faster than a dog in the real world but for the sake of the argument this is a fact because it is presented as such. There are no words in the sentence that lead to ambiguity.

2) Assumption: This is something that is not directly stated in the passage but MUST be inferred in order to reach the conclusion.

ex. All girls over 5 ft tall are good at basketball, therefore Stacy is good at basketball.

The assumption is that Stacy is over 5 ft tall. Without that assumption the conclusion that Stacy is good at basketball makes no sense.

3) Conclusion: The conclusion is something that is stated in the the passage but is not presented as fact. It is the opinion derived from the facts. It is all a matter of wording.

ex. Therefore, all dogs are faster than cats.

This is similar to the first sentence but in this case it is not presented as fact. The word 'therefore' signals that this is something that is trying to be proven.

For example you would not say I have lived for 30 years, therefore I'm 30. If your 30 years old that is a fact and you present it as such. I am 30 years old. But if you don't know for sure how old you are you could say something like: "I have a picture showing that I was born in 1978 therefore I must be 30."

So the first thing I do is figure out what the question is asking me.

Knowing which one of the following would be most useful in evaluating the argument?

So whenever I see argument I think conclusion. The conclusion IS the argument. You don't argue facts, you argue your conclusion based on facts.

So we are looking for information that will be helpful in evaluating the conclusion.

So I break out the conclusion from the premises.

Premise: the chances that a planet capable of supporting life will be formed are high.

Premise: The chances that a large planet the size of Jupiter or Saturn will be formed, however, are low.

Premise: Without Jupiter and Saturn, whose gravitational forces have prevented Earth from being frequently struck by large comets, intelligent life would never have arisen on Earth.

Conclusion: Since planetary systems are unlikely to contain any large planets, the chances that intelligent life will emerge on a planet are, therefore, low.

So now it clearer what information I'm looking for. I'm looking for information that will help me evaluated if the CHANCES that intelligent life will emerge on a planet are low.

The only things that affect these chances are.

1) Chances of a planet capable of supporting life
2) Chances of a large planet to deflect large comets
3) Chances life could survive a large comet strike
4) Chances that there are comets capable striking the planet

1, 2, 3, are already given and stated as fact. The only chance that we don't already know is the chance that a comet will strike the planet.

That is given in D.
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Re: CR - planetary system  [#permalink]

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28 Jul 2010, 00:20
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Well, B and D clearly are the choices which are worthy of further evaluation on a test day. I chose B but I understand that it is not the perfect choice considering the argument talks of the "emergence" of intelligent life whereas option B talks about survival. Technically, emergence (birth, beginning) is different from survival.

But here's my problem with D: the option says "how high the chances are that planetary systems will contain many large comets". In my view, while the existence of large comets is critical for the conclusion to hold true, nowhere in the argument is there an evidence that "many" large coments are required for a planet to be "frequently struck by large comets". It may well be the case that one or two large comets are responsible for frequent strikes to the Earth. If that is the case, the presence / absence of "many" large coments does not have a bearing on the conclusion. What will make more sense is an aswer choice which states that "how high the chances are that planetary systems will contain any large comets"

Makes sense?
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Re: When a planetary system forms, the chances that a planet  [#permalink]

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06 Aug 2010, 05:30
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Conclusion : Since planetary systems are unlikely to contain any large planets, the chances that intelligent life will emerge on a planet are, therefore, low. -------->
Since the chances of large planets are low. That means we have less Jupiters and Saturns that deflect the comet. The argument rests on the number of comets in the planetary system. The more the comets the faster the extinction of the intelligent life.

B is out of whack LOLs. I hope that never happens.

(C) whether large comets could be deflected by only one large planet rather than be two ---> OUT for the reason above

(D) how high the chances are that planetary systems will contain many large comets ----> Yes this is essential to the argument. In the absence or less Jupiters and Saturns we need to evaluate the probability or the number of comets in the planetary system which are in collision course with the intelligent planets such as Earth.

(E) how likely it is that planetary systems containing large planets will also contain planets the size of Earth -----> This evaluation is useless. The argument rests on the number of comets NOT on the number of intelligent planets.

jananijayakumar wrote:
What's the OA? I'm completely lost...
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Re: When a planetary system forms, the chances that a planet  [#permalink]

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02 Aug 2012, 05:23
1
The fundamental problem with B I thought was not that there is a Survival or Emergence issue. The problem was it goes beyond the argument, Hence out of scope. When you have out of scope, answering the question still means that you will have to speculate at some level.

E.g. Even if we knew that the species survived after a large comet attack, how would that help us evaluate whether chance of survival of the remaining species.
Let's say two comets would wipe out the planet but 1 planet allows the species to survive. You would still need to know how many comets are going to hit the planet, right? So, this ambiguity means I can't really say whether statement B helps me assess the chances of survival or emergence of the species on the planet.
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Re: CR - planetary system  [#permalink]

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02 Aug 2012, 12:52
1
deepakdewani wrote:
Well, B and D clearly are the choices which are worthy of further evaluation on a test day. I chose B but I understand that it is not the perfect choice considering the argument talks of the "emergence" of intelligent life whereas option B talks about survival. Technically, emergence (birth, beginning) is different from survival.

But here's my problem with D: the option says "how high the chances are that planetary systems will contain many large comets". In my view, while the existence of large comets is critical for the conclusion to hold true, nowhere in the argument is there an evidence that "many" large coments are required for a planet to be "frequently struck by large comets". It may well be the case that one or two large comets are responsible for frequent strikes to the Earth. If that is the case, the presence / absence of "many" large coments does not have a bearing on the conclusion. What will make more sense is an aswer choice which states that "how high the chances are that planetary systems will contain any large comets"

Makes sense?

I agree with your assessment and i arrived at the same conclusion.
Choice (D) looks to me like a classic shell answer. One that contains all the right words, but doesn't provide any additional relevant data.
As per the premises, The sole purpose of large planets such as Jupiter and Saturn is to deflect comets. That's the premise. However, we need to understand if the danger from comets is very real, or if it is exaggerated. . Think of it this way. Many countries stock pile nuclear weapons, claiming that these weapons serve as deterrents. So to understand if nuclear weapons are required, one needs to understand if the threat from other countries is real, or an imagined one.

Back to the question...How does it matter, if a planetary system contains many comets, if these comets dont strike the planets which support life.
These comets may be in totally different orbits and may never collide with the planets.

I would agree with (D), if the answer choice was worded as follows
How high are the chances of deadly collisions between comets and the planets.
If the chances are very low, then this implies that the "deflecting services" of the large planets are unnecessary.
If the chances are high, then this implies that the "deflecting services" of the large planets are very necessary.
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When a planetary system forms, the chances that a planet  [#permalink]

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08 Aug 2015, 06:58
priyankur_saha@ml.com wrote:
When a planetary system forms, the chances that a planet capable of supporting life will be formed are high. The chances that a large planet the size of Jupiter or Saturn will be formed, however, are low. Without Jupiter and Saturn, whose gravitational forces have prevented Earth from being frequently struck by large comets, intelligent life would never have arisen on Earth. Since planetary systems are unlikely to contain any large planets, the chances that intelligent life will emerge on a planet are, therefore, low.

Knowing which one of the following would be most useful in evaluating the argument?

(A) whether all planetary systems are formed from similar amounts of matter
(B) whether intelligent species would be likely to survive if a comet struck their planet
(C) whether large comets could be deflected by only one large planet rather than by two
(D) how high the chances are that planetary systems will contain many large comets
(E) how likely it is that planetary systems containing large planets will also contain planets the size of Earth

Good question !!!

Most of the confusion is between B and D.

B is a trap !!

Although B looks fine but subtly diverges from the conclusion. Conclusion is about emergence of intelligent life not about survival of intelligent life. OK granted that the intelligent species will not survive if a comet struck BUT that ACTUALLY proves that the intelligent life did emerge ( because then only it can be annihilated. How can you annihilate something that did not exist in the first place. ) . Same argument cane be made for the case in which the intelligent life will survive the catastrophe.

Now the game changer D.

The argument tells us that the BIG planets affect chances of the emergence of intelligent life on a planet because the biggies help deflect the monster comets.

But what if there are no large comets in the planetary system?Do we still require large planets in such a situation? If there are no monster comets then the chances are high.
that intelligent life will emerge.
What if the planetary system is likely to have large comets? Oh yes..then we do we need planets to deflect these monsters to help intelligent life emerge.

The requirement to have LARGE planets is useful only if there are large comets in the planetary system.

Hope the above helps!!

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When a planetary system forms, the chances that a planet  [#permalink]

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28 Jul 2018, 18:09
When a planetary system forms, the chances that a planet capable of supporting life will be formed are high. The chances that a large planet the size of Jupiter or Saturn will be formed, however, are low. Without Jupiter and Saturn, whose gravitational forces have prevented Earth from being frequently struck by large comets, intelligent life would never have arisen on Earth. Since planetary systems are unlikely to contain any large planets, the chances that intelligent life will emerge on a planet are, therefore, low.

Knowing which one of the following would be most useful in evaluating the argument?
---------------
What is good in "evaluating" questions, you can answer any option (that seems good to you, or really any option) in two opposite ways and see if they give the opposite effects. If yes, it will probaly be the answer.

(A) whether all planetary system are formed from similar amounts of matter
Well. It gives us absolutely nothing. We can make of course very far speculations, but reall out of scope

(B) whether intelligent species would be likely to survive if a comet struck their planet
Sounds good. If intelligent species can survive after a strike of a comet, then all is ok, if they can not survive, then all is not ok. Perfect. But!
What if after the first strike it is he second onem the third, ...?
Suppose that that the probability of intelligent species to survive after comet's strike is 90%. Ok. 1st strike ---> we have 90% chance of survival - it is big (actually not, but lets say it is big, for our purposes)
But if it is 10 strikes in 100 years for example. The probability that none of these stikes will destroy the life wil be 0.9*0.9*...0.9 (10 times) = 34,8678% - does not sond very good
Lets keep it (but it is already pretty clear that it will unlikely be the right answer) and see other options.

(C) whether large comets could be deflected by only one large planet rather than be two
Speculations. Does not matter. The most interesting case for us (the only one) is the case when we do not have large planets-protectors at all.

(D) how high the chances are that planetary systems will contain many large comets
This is very good. It eliminate the issue of C.
If there a lot of of large comets in the planetary system, then eventually some of them will strike the "intelligent" planet and eventually will kill the life here (if it is pretty large)
If there a small amount of large comets in the planetary system, then maybe even none of them ever will hurt the planet, or if it eventually does, maybe it will not kill the life (the small comets can hot the planet on a regular basis, it will not have much effect)

(E) how likely it is that planetary systems containing large planets will also contain planets the size of Earth
Absolutely irrelevant. The passage itself supposes that there is a planet of Earth's size. So this option even contradicts the passge

So, D.
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Re: When a planetary system forms, the chances that a planet  [#permalink]

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29 Jul 2018, 20:27
I still am not sure why option B is not correct. The way i see it if the species survival is key & this seems to address the issue directly.
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Re: When a planetary system forms, the chances that a planet  [#permalink]

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29 Jul 2018, 20:44
lazybee wrote:
I still am not sure why option B is not correct. The way i see it if the species survival is key & this seems to address the issue directly.

The fight was between B and D. Both may seem correct at first, however, a small detail that B does not consider makes it a bad option. B takes into account ALL the comets be it a small one or a large one.

Quote:
whether intelligent species would be likely to survive if a comet struck their planet

The biggest mistake would be to assume that 'a comet' refers to the one in question.

Option D, on the other hand, says
Quote:
(D) how high the chances are that planetary systems will contain many large comets

It clearly refers to the type of comets in consideration.

A reason that made me tend towards B was that D says there could be places where there are no/few comets, but that defies cosmological logic - THIS REQUIRES YOU TO MAKE AN ASSUMPTION - INCORRECT ON THE GMAT
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When a planetary system forms, the chances that a planet  [#permalink]

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21 Nov 2018, 11:59
gixxer1000 wrote:
I get D.

Premise: the chances that a planet capable of supporting life will be formed are high.

Premise: The chances that a large planet the size of Jupiter or Saturn will be formed, however, are low.

Premise: Without Jupiter and Saturn, whose gravitational forces have prevented Earth from being frequently struck by large comets, intelligent life would never have arisen on Earth.

Conclusion: Since planetary systems are unlikely to contain any large planets, the chances that intelligent life will emerge on a planet are, therefore, low.

The conclusion of the argument is based on the facts that large planets are needed to pull large comets away from the smaller planets that can support life. If there are no comets to pull away then the conclusion fails.

Why do we think comets can only come from inside the same planetary system, why not outside?
When a planetary system forms, the chances that a planet &nbs [#permalink] 21 Nov 2018, 11:59
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