Logical Reasoning

PT103 · S1 · Q11 Five thousand of the 50,000 books

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Five thousand of the 50,000 books published in country Z in 1991 were novels.

Conclusion

No more than 1/4 of the films released in country Z in 1992 were based on books published in Z in 1991.

Evidence (since)

100 films were released in country Z in 1992. 25 of the films released in country Z in 1992 were based on novels published in Z in 1991.

Evaluate

The conclusion is talking about one-quarter because 25 is one quarter of 100. We could replace the word "one-quarter" with 25 if that helps us think about it.

Does the evidence prove that no more than 25 out of the 100 films from 1992 were based on books published in 1991.

Not quite. The evidence establishes that 25 out of the 100 films from 1992 were based on novels published in 1991. But the conclusion has made a move from "only 25 were based on 1991 novels" to "only 25 were based on 1991 books".

It might be that the 100 films of 1992 are broken down like this: 25 - based on 1991 novels 20 - based on 1991 nonfiction books 55 - not based on a book at all

This would make the author's conclusion wrong, because more than 1/4 (45 out of 100) of the films from 1992 were based on books.

Goal

We can think of the job the answer needs to do in a positive or a negative way.

Positively, we need our answer to be saying .

Negatively, we can think that our answer needs to rule out the objection that . So it could sound like, .

11.

Which one of the following, if assumed, allows the conclusion above to be properly drawn?

None of the scripts used
Out of Scope: scriptwriters
We don't care at all who wrote these scripts. We know that 25 of them were based on 1991 novels, and the only thing we need to know about the remaining 75 of them is whether any of them were based on non-novel books from 1991.
0% picked this
Correct
None of the films released
Why this is right
We know that 25 of the 100 films were based on 1991 novels, and the only thing we need to know about the remaining 75 of them is whether any of them were based on non-novel books from 1991. According to this answer, none of the 100 were based books other than novels, so there's no chance that any of the remaining 75 films were based on a non-novel book. Thus, this answer proves that the 25 films based on novels are the only 25 films based on any books from 1991. We could think of this answer as giving us a conditional that says if a 1992 film was ? then it was based based on a book on a novel By contrapositive, if not based on novel, not based on book We know that only 25 were based on novels. The remaining 75 were not based on novels. So according to this rule the remaining 75 were not based on books. Thus, we are able to derive that no more than 1/4 (no more than 25 of the 100 films) were based on books.
Skill tested: Sufficient Assumption · how this choice captures the argument's function is the move to repeat next time.
79% picked this
None of the books that
Out of Scope
Out of Scope: based on film plots We don't care at all whether some books were based on films. We know that 25 of the 100 films in 1992 were based on 1991 novels, and the only other thing we need to know about the remaining 75 films is whether any of those films were based on non-novel books from 1991.
4% picked this
Some of the films released
Out of Scope
Out of Scope: based on older films We don't care at all whether some films were based on older films from prior to 1991. We know that 25 of the 100 films in 1992 were based on 1991 novels, and the only other thing we need to know about the remaining 75 films is whether any of those films were based on non-novel books from 1991.
7% picked this
Some of the films released
Out of Scope: 1991 films
We don't care at all what 1991 films were based on. We know that 25 of the 100 films in 1992 were based on 1991 novels, and the only other thing we need to know about the remaining 75 films is whether any of those films were based on non-novel books from 1991.
10% picked this

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