Q11 - Five thousand of the 50,000

[weiyichen1986]

Hi, i am wondering why is answer D incorrect on this one? Thanks

[ohthatpatrick]

Most of the time on LSAT, we work from Wrong to Right.

The big exception is Sufficient Assumption. The correct answer must prove the conclusion is true beyond the shadow of a doubt.

All the incorrect answers do not prove the conclusion is true.

So the short answer is that (D) is wrong because it doesn't prove that the conclusion is true.

To understand the missing piece of info we want to seal the deal with the conclusion, let's break down the core:

Conc:
25% or less of 1992 films were based on 1991 books.

Prem:
1991: 5000 novels, 45000 non-novel (nonfiction) books published.
1992: 25 films were based on 1991 novels. 100 films released total.

This is a very math-y argument, so let's make sure we get the reasoning.

The author is saying that
"25 out of 100 films released in 1992 were based on 1991 novels."

Does that prove the conclusion that
"only 25% of the films released in 1992 were based on 1991 books"?

Well, 25 out of 100 = 25%.

But "novels" (in the premise) does not equal "books" (in the conclusion).

So there's our wiggle room.

What if, in 1992, there were 25 films based on 1991 novels and another 10 films based on 1991 nonfiction books?

That would mean that 35 out of 100 films from 1992 (more than a quarter) were based on 1991 books.

That would contradict the conclusion.

So the truth or falsity of the conclusion hinges solely on whether any of the other 75 films released in 1992 were based on 1991 "non-novel" books.

(B) settles that issue definitively. It says that all of the book-based films in 1992 were based on novels. That means that our 25 novel-based films are the only book-based films out of the 100 total films from 1992.

(D) does not settle that issue. In fact it doesn't address the issue of films being based on books at all. It discusses the issue of films being based on older films, which has nothing to do with our argument core.

Sufficient Assumption questions have some very reliable tendencies:
1. The correct answer will almost ALWAYS be super-strongly worded: all, always, each, any, no, none, never, unless, only, must, cannot

Wording that leaves room for exceptions or doubt does not accomplish what we need out of the answer: PROVING the conclusion is true.

So if you were to take a clueless guess on this problem, you would definitely guess from A/B/C, rather than the "some" statements in (D) and (E).

And "professionals" in (A) and "plots" in (C) are out of scope.

But ultimately, as I said at the outset, it's much more important that you understand why (B) is correct on this problem. If you understand the missing piece we need to prove the conclusion, then the four incorrect answers are all wrong because they're not right.

Hope this helps. Let me know if you want any clarification.

[WaltGrace1983]

(A) is completely out of scope...who cares WHO wrote these scripts?

(B) is correct for the very detailed reasons above

(C) seems to reverse the argument. We are talking about films that are based on books but this is talking about books that are based on films.

Is (E) completely out of scope because we are talking about films released in 1991 when the argument is talking about films released in 1992?

Also, would (D) be a (really weak) strengthener of the argument? If we say that "no more" than 25% of the films are based on books while saying that "some" were based on older films, does this make it (albeit very slightly) more plausible that the conclusion is correct based on the premises? Yes I know that (B) is the gap but I am trying to learn as much from these questions as possible

[christine.defenbaugh]

Great thinking WaltGrace1983! Awesome eliminations!

And yes, the fact that (E) talks about films released in 1991 instead of 1992 makes it entirely irrelevant!

For (D) to even begin to strengthen, you would have to make the assumption that a movie could not be based on both an older movie and a recent book at the same time. That might seem reasonable at first, but there's really no reason why it would have to be one or the other!


I love how hard you are working to see the bigger logical picture and make connections across question types! Keep it up!