Expert: A group of researchers claims to have shown that for an antenn

Question

Expert: A group of researchers claims to have shown that for an antenna to work equally well at all frequencies, it must be symmetrical in shape and have what is known as a fractal structure. Yet the new antenna developed by these researchers, which satisfies both of these criteria, in fact works better at frequencies below 250 megahertz than at frequencies above 250 megahertz. Hence, their claim is incorrect.

The reasoning in the expert’s argument is flawed because the argument

The reasoning in the expert’s argument is flawed because the argument

(A) fails to provide a definition of the technical term “fractal”
(B) contradicts itself by denying in its conclusion the claim of scientific authorities that it relies on in its premises
(C) concludes that a claim is false merely on the grounds that there is insufficient evidence that it is true
(D) interprets an assertion that certain conditions are necessary as asserting that those conditions are sufficient
(E) takes for granted that there are only two possible alternatives, either below or above 250 megahertz

Bunuel · Accepted Answer

EXPLANATION FROM Fox LSAT

This argument confuses a condition that is necessary for a given outcome to be sufficient for that same outcome. The argument basically says, “Scientists claim that to be in San Francisco, you must be in California. But George is in California, and he is not in San Francisco, therefore the scientists are mistaken.” Yes, it really is that simple.

A) No way, we’re looking for “confuses a necessary condition with a sufficient condition” or its equivalent.

B) Again, not what we’re looking for.

C) Not what we’re looking for.

D) Boom.

E) Not what we’re looking for, and D was  exactly  what we were looking for, so D is our answer.

Our answer is D.

IanStewart · Answer

I just posted a reply to a similar question an hour ago, here, so I won't repeat the theory here, but this argument also confuses sufficient conditions with necessary conditions. We know we need a symmetrical and fractal antenna for the antenna to work equally well at all frequencies. So those conditions are necessary, but we don't know if they're sufficient -- in fact they probably aren't, because an antenna presumably needs other qualities to even work at all, let alone to work equally well at various frequencies. So the answer is D.

These logical issues (sufficient vs necessary conditions, converse or inverse vs contrapositive) are frequently tested on the LSAT, but aren't often tested on the GMAT (and when they are, the style of the question is not similar to the style of this one).

These logical issues (sufficient vs necessary conditions, converse or inverse vs contrapositive) are frequently tested on the LSAT, but aren't often tested on the GMAT (and when they are, the style of the question is not similar to the style of this one).

NeoNguyen1989 · Answer

This is a typical necessary vs sufficient condition. The researchers’ work depends on the necessary conditions of fractal structure and symmetrical shape. These conditions, however, do not guarantee the desired outcome. The expert misunderstood that. For the correct answer choice, just need to find the one with necessary-sufficient condition. D fit the profile perfectly

Posted from my mobile device

Posted from my mobile device

Crytiocanalyst · Answer

(A) fails to provide a definition of the technical term “fractal”
The term is well brified in the passage therefore out

(B) contradicts itself by denying in its conclusion the claim of scientific authorities that it relies on in its premises
The contradiction is fine however the flaw is not because of the above stated one therefore out

(C) concludes that a claim is false merely on the grounds that there is insufficient evidence that it is true
The data sufficiency was never questioned as even one experiment is more than justify or deny a fact therefore out

(D) interprets an assertion that certain conditions are necessary as asserting that those conditions are sufficient
This is exactly the intended reasoning therefore let us hang on to it

(E) takes for granted that there are only two possible alternatives, either below or above 250 megahertz
The above possibilities were scrutunized but was never narrowed to this possibility alone therefore out

Therefore IMO D

Sushen · Answer

Technique for FLAWS:
• Identify the conclusion
• Know that you cannot get to the conclusion b/c there is one of 20 or more flaws present in the argument. The flaw in the reasoning means the conclusion CANNOT be reached.
• Your job (preferably) is to know the types of flaws in logical reasoning arguments and to describe the flaw. The correct answer is this description.
• You will do best if you PREDICT the flaw that is present in the argument.

Conclusion: Hence, their claim is incorrect.
That, “for an antenna to work equally well at all frequencies, it must be symmetrical in shape and have what is known as a fractal structure” is incorrect.
There is conditional reasoning here. They MUST have switched the sufficient for the necessary!!!!
Argument: Must is a necessary indicator:
 Symmetrical and have fractal structure
Now add the rest of the sentence as the sufficient:
IF Antenna to work equally well at all frequencies  THEN it is symmetrical and has a fractal structure.
New data/new antenna 
NEGATES the sentence:
NOT word equal at all freq  NOT sym and fractal structure. 
Negating an if then is switching the sufficient and the necessary on the contrapositive.
This flaw may simply be: YOU CAN’T just negate a conditional logic “sentence” 
D!!!! Switches the sufficient for the necessary!!!!!

Expert: A group of researchers claims to have shown that for an antenn

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Expert: A group of researchers claims to have shown that for an antenn

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