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11-year sunspot cycle

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11-year sunspot cycle

by Ankitaverma » Sat Dec 07, 2013 12:27 pm
After observing the Earth's weather patterns and the 11-year sunspot cycle of the Sun for 36 years, scientists have found that high levels of sunspot activity precede shifts in wind patterns that affect the Earth's weather. One can conclude that meteorologist will be able to improve their weather forecasts based on this information.

Which of the following, if true, most seriously weakens the argument above?

(A) Weather forecasts are more detailed today than they were 36 years ago.
(B) Scientists can establish that sunspot activity directly affects the Earth's weather.
(C) Evidence other than sunspot activity has previously enabled meteorologists to forecast the weather conditions that are predictable on the basis of sunspot activity.
(D) Scientist have not determined why the sunspot activity on the Sun follows an 11-year cycle.
(E) It has been established that predictable wind patterns yield predictable weather patterns.

Q/a-c
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by RajeevGmatTaget700 » Sun Dec 08, 2013 8:37 am
The answers has to be C.

Any weaken q on the CR has to directly/indirectly hit the assumption. So the assumption here is that the meteorologists can predict weather on only the sunspot activity.

Answer choice c does exactly the opposite by saying that there are other ways to do the same.
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by [email protected] » Sun Dec 08, 2013 10:53 pm
Hi Ankitaverma,

Rajeev has presented the correct logic behind the correct answer, but I'm going to add a few details.

This prompt presents us with some facts and a conclusion:

The Facts:
Scientists have linked sunspot activity with wind patterns that affect the Earth's weather.
Scientists have lots of data going back 36 years.

The Conclusion:
Meteorologists will be able to improve their weather forecasts with this info.

The Logic:
The sunspot patterns should continue to serve as an indicator of wind patterns, so this new information will help Meteorologists to improve their forecasts.

To weaken this prompt, we have to find an answer that destroys the logic. There's usually more than one way to weaken the logic, so you need a general idea of what you're looking for. I'd be looking for an answer that tells us that meteorologists forecasts WON'T get better for some reason; if I can't find THAT, then I'd be looking for an answer that tells us that something has changed and sunspots currently don't precede wind patterns the way that they used to.

The only answer that properly fits is C; it tells us this new info won't help meteorologists to improve their predictions because they were already making predictions at this level of accuracy.

GMAT assassins aren't born, they're made,
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by abhasjha » Mon Dec 09, 2013 12:45 am
Hi Ankitaverma,

One. Of the ways In which you can weaken a cause effect relations is to find alternate cause ... What is the cause given in the stimulus ? High level of. Sunspot activity .... What is the effect ? Earth weather is effected.

Now if there exist an alternate explanation to the cause .... Then. Our conclusion Will be weakened....

Option c. States that other cause for earth weather being affected . This therefore weakens the conclusion.
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by Abhishek009 » Mon Dec 09, 2013 7:42 am
Ankitaverma wrote:After observing the Earth's weather patterns and the 11-year sunspot cycle of the Sun for 36 years, scientists have found that high levels of sunspot activity precede shifts in wind patterns that affect the Earth's weather. One can conclude that meteorologist will be able to improve their weather forecasts based on this information.
P:Observation of Sunspot cycle , was done for 36 years.

P :High Level of Sunspot Activity ----------->followed by ----------> Shifts in wind patterns( Affecting Earth's Weather)

C :Meteorologist will be able to improve their weather forecasts

Which of the following, if true, most seriously weakens the argument above?


Our target is to Attack the conclusion given over here -

One can conclude that meteorologist will be able to improve their weather forecasts based on this information.

(A) Weather forecasts are more detailed today than they were 36 years ago.

Might be true but it is no way attacking the conclusion , hence rejected. We can no way prove from this statement that the conclusion is false.

(B) Scientists can establish that sunspot activity directly affects the Earth's weather.

Sunspot cycle precedes change in weather and it is almost strengthening the targeted statement , hence rejected.

(C) Evidence other than sunspot activity has previously enabled meteorologists to forecast the weather conditions that are predictable on the basis of sunspot activity.

The highlighted part bring something new into consideration directly challenging the targeted statement . It suggests that it was previously possible to forecast weather conditions , on the basis of Sunspot activity , hence we can keep this solution aside and check for the other options..

(D) Scientist have not determined why the sunspot activity on the Sun follows an 11-year cycle.

Way out of Scope.

(E) It has been established that predictable wind patterns yield predictable weather patterns.

This is just a casual statement without any relation to the discussion under consideration...


So Option (C) seems the best..
Abhishek
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