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- rob.schimmel
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Vinny Gambini
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PT49, S2, Q7 Any fruit that is infected
I understand that E is right, but I chose B when I saw it and moved on. Any tips on how to spot B as a wrong answer type?
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- noah
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Atticus Finch
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Re: E49, S2, P7
Preptest 49 June 2006 LSAT Answers
Hi Rob,
To answer your question about approach, this sort of question, in which it almost seems that the LSAT has hardly bothered to put words to the logical statements underneath, you may want to try diagramming. That said, I find that's more helpful when I need to find a legal inference. For assumption questions dealing with this type of argument, be very vigilant for logical holes -- which topics are disconnected? See if diagramming makes this easier for you (I am generally wary of getting people hooked on that as one can lose sight of the argument's meaning and structure through a focus on the notation -- imagine if you mis-write something). Play around and see what works for you.
Here's a more formal explanation of the problem:
7. (E)
Question type: Inference
This argument contains a number of logical statements, the first two of which are premises: Infected -> Rotten, and Inspected -> Not Infected. The third and concluding statement is that Inspected -> Safe to eat. This question is made more complex by the fact that "infected" and "inspected" are easily mistaken for each other. Another complication is that the second premise is worded in a complicated manner. "No fruit that is inspected is infected" does not mean Not Inspected -> Infected! Consider what the following means: "No child of mine is going to eat marshmallows for dinner!" That means that if you are indeed a child of this nutritional maniac, you will not eat marshmallows (Child of mine - > No marshmallow dinner).
In this problem, a premise is clearly missing since the conclusion introduces a new idea"”whether it’s safe to eat something"”and so the answer must introduce that idea and connect it to the existing premises. One simple manner to do this, as answer choice (E) does, is to establish that uninfected fruit is safe to eat, creating this logical statement: Inspected -> Not Infected - > Safe to Eat.
The contrapositives of the given premises are: Not Rotten - > Not Infected, and Infected -> Not Inspected. Neither of these allows us to make a longer chain with the original statements (these would have to begin with either Rotten or Not Infected to do that).
The other answer choices mention food safety, however none of them connect that to the inspection of food, either directly or indirectly (through "Not Infected", the result of having been inspected). Answer choice (B) is particularly tempting as it seems somewhat reasonable, but within the argument, it does not connect inspections to food safety. (C) does link inspections and food safety, however the argument has already established that if fruit has been inspected, it is not infected. Therefore, it doesn’t matter whether that infected (and inspected) food is safe to eat, as that fruit is not the fruit that in reality was inspected.
If all the logical chains confuse you, consider the problem in real-life terms (though to master the LSAT, you’ll need to be able to work with logic disconnected from reality). A box of fruit is inspected and the inspector declares all the fruit to be uninfected. A child sitting nearby then goes to grab a piece of fruit, assuming that means the fruit is therefore safe to eat, but then that child’s mother stops him, saying "it might be uninfected, but perhaps you’re allergic to it!." The child and mother look up at the inspector and she says, "It is safe to eat any fruit that is uninfected!" What a relief!
Hi Rob,
To answer your question about approach, this sort of question, in which it almost seems that the LSAT has hardly bothered to put words to the logical statements underneath, you may want to try diagramming. That said, I find that's more helpful when I need to find a legal inference. For assumption questions dealing with this type of argument, be very vigilant for logical holes -- which topics are disconnected? See if diagramming makes this easier for you (I am generally wary of getting people hooked on that as one can lose sight of the argument's meaning and structure through a focus on the notation -- imagine if you mis-write something). Play around and see what works for you.
Here's a more formal explanation of the problem:
7. (E)
Question type: Inference
This argument contains a number of logical statements, the first two of which are premises: Infected -> Rotten, and Inspected -> Not Infected. The third and concluding statement is that Inspected -> Safe to eat. This question is made more complex by the fact that "infected" and "inspected" are easily mistaken for each other. Another complication is that the second premise is worded in a complicated manner. "No fruit that is inspected is infected" does not mean Not Inspected -> Infected! Consider what the following means: "No child of mine is going to eat marshmallows for dinner!" That means that if you are indeed a child of this nutritional maniac, you will not eat marshmallows (Child of mine - > No marshmallow dinner).
In this problem, a premise is clearly missing since the conclusion introduces a new idea"”whether it’s safe to eat something"”and so the answer must introduce that idea and connect it to the existing premises. One simple manner to do this, as answer choice (E) does, is to establish that uninfected fruit is safe to eat, creating this logical statement: Inspected -> Not Infected - > Safe to Eat.
The contrapositives of the given premises are: Not Rotten - > Not Infected, and Infected -> Not Inspected. Neither of these allows us to make a longer chain with the original statements (these would have to begin with either Rotten or Not Infected to do that).
The other answer choices mention food safety, however none of them connect that to the inspection of food, either directly or indirectly (through "Not Infected", the result of having been inspected). Answer choice (B) is particularly tempting as it seems somewhat reasonable, but within the argument, it does not connect inspections to food safety. (C) does link inspections and food safety, however the argument has already established that if fruit has been inspected, it is not infected. Therefore, it doesn’t matter whether that infected (and inspected) food is safe to eat, as that fruit is not the fruit that in reality was inspected.
If all the logical chains confuse you, consider the problem in real-life terms (though to master the LSAT, you’ll need to be able to work with logic disconnected from reality). A box of fruit is inspected and the inspector declares all the fruit to be uninfected. A child sitting nearby then goes to grab a piece of fruit, assuming that means the fruit is therefore safe to eat, but then that child’s mother stops him, saying "it might be uninfected, but perhaps you’re allergic to it!." The child and mother look up at the inspector and she says, "It is safe to eat any fruit that is uninfected!" What a relief!
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