Not surprisingly, there are no professors under the age of eighteen.

Question

Not surprisingly, there are no professors under the age of eighteen. And as is well known, no one under eighteen can vote legally. Finally some brilliant people are professors, some are legal voters, and some are under eighteen.

If the statements above are true, then on the basis of them which one of the following must also be true?

(A) No professors are eighteen-year-olds.

(B) All brilliant people are either professors, legal voters, or under eighteen.

(C) Some legal voters are not professors.

(D) Some professors are neither legal voters nor brilliant people.

(E) Some brilliant people are neither professors nor legal voters.

AndrewN · Accepted Answer

Hello,  honey1 . To answer your last question first, you may want to explore different ways of approaching the same question. Some people will swear by diagramming; others, like myself, write nothing down. But in either case, practice is essential to be able to spot the logical underpinnings of a passage. Consider choice (C) again:

For this to be true  necessarily  (i.e. to fit a must-be-true condition), we need to find information about voters who are definitely  not  professors. What does the passage tell us? It is not until the final line that we get any information about brilliant (but not necessarily professorial) people.

To summarize:

1) No professors are under 18.
2) No one under 18 can legally vote.
3.1)  Some  brilliant people are professors. (Therefore, these brilliant people  must  be 18+.)
3.2)  Some  brilliant people are legal voters. (Therefore, these brilliant people  must  be 18+.)
3.3)  Some  brilliant people are under 18. (Therefore, this subset of brilliant people  must not  be professors or legal voters.)

As you can see, we have no information about the voting population, in terms of the professions people hold. We cannot say for certain whether  any  of these brilliant professors are the same people who comprise  legal voters . The term  some  is too vague. But we can use that same understanding to qualify choice (E), as statement 3.3) shows above.

I hope that helps. I have done the best I can to try to trace my thought process.

- Andrew

stne · Answer

NOTE: Question says MUST be true and NOT can be true.
So if we can prove that an option MUST NOT necessarily be true ( can be false ) then we can eliminate that option. The right option cannot be falsified .

So you cannot be a professor, if you are below 18 unless you are Brilliant. .................(1)
To be a legal voter you must be above 18 and you may or may not be a professor......... (2)
If you are brilliant and below 18 , you are definitely NOT a legal voter, you may or may not be a professor..(3)

(A) No professors are eighteen-year-olds: Actually We have info. for  ONLY  under 18, nothing is said about  EXACTLY  18 years old, hence we cannot deduce anything from the statement and Since this statement is not based on the argument it is outside scope hence need not necessarily be true. Irrelevant INCORRECT

(B)Last line of the argument clearly says some brilliant people are professors, some are legal voters, and some are under eighteen: So  "ALL"  in this option is definitely not true.  INCORRECT.

(C) Actually nothing is given in the argument about this. Since this statement is not based on the argument it is outside scope Hence we cannot deduce anything from this, hence need not be true.  Irrelevant INCORRECT. i.e.In a group of professors who are above 18, all are legal voters.

(D) Some professors are neither legal voters nor brilliant people: Well, if you are a professor, and NOT a legal voter( i.e you are below 18 ) then you must be Brilliant . Hence this option is definitely NOT true.  INCORRECT.

(E)Because a Brilliant person can be below 18, the below 18 person cannot be a legal voter. So some brilliant people need not be legal voters (Nor professors)  point no.3  in the explanation , definitely true.  CORRECT.

The word SOME in C, makes it a bit tricky.But since C is outside scope of the argument, we should not assume it is true.Between C and E , option E is definitely stronger.

Hope it's clear.

honey1 · Answer

hey can you plz help me with this question 
how can option c be eliminated if some legal voter are professor then some legal voter will not be professor so what's wrong with it
i also want to ask i should focus on diagramming the conditions or on reasoning

vasu1104 · Answer

Option A- doesn’t make sense to consider 
Option B - tempting at first but when you go deep to understand logic, you will find a flaw.
Option C - we only know that professor cant be under age of 18 so this option doesnt make sense
Option D - this option actually got me for few seconds but then if there are some professor then you must be above 18 and allowed to vote. This options says opposite to that.
Option E - only left with this one now and it actually make sense given the information given in the paragraph.

Posted from my mobile device

VerbalBot · Answer

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Not surprisingly, there are no professors under the age of eighteen.

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