PrepTest 154

Incorrect. This isn't supported by the argument. For one thing, we don't know whether or not her early-career, unoriginal works were popular with collectors.

Incorrect. This also isn't supported. Even after she began producing highly original works late in her career, she might have continued also making unoriginal works. Or, late in her career could have been when she made her few (if any) abstract works that are highly original.

Incorrect. Again, we don't know enough about how much she produced late in her career. This is an implied converse fallacy; the answer choice is behaving as if the rule was Late in Career ==> Highly Original, rather than Highly Original ==> Late in Career.

Correct. Argument or Facts:
Facts

Question Type:
Must Be True

Stimulus Summary:
1) Oil Paintings ==> Highly Original
2) Oil Paintings-most-not Critically Acclaimed
3) Oil Paintings-most-not Popular
4) Highly Original ==> Late in Career
5) Abstract-most-not Highly Original

Answer Anticipation:
There's a LOT going on in this stimulus, with many conditional and quantifier statements included. You can work through all of the statements and try to combine them, but, generally when there are this many, it can be faster to clearly write them out, and then move on to the answer choices to see which of them look like they will come from combinations.

Additionally, note one important feature here: "few do" becomes "most don't". That's the logic statement you can derive from a "few do" statement—not that some do, but that most don't. It's a tricky one, so look out for it! We also split the "or" statement into two individual statements, which you can do when it's on that side of the arrow.

We definitely want to take the time to create the contrapositives here. We can't do that with "Most" statements, so we just get contrapositives for the two "All" statements:

1) Not Highly Original ==> not Oil Paintings
4) not Late in Career ==> not Highly Original

With the aid of those, we can obtain the following conclusions:

Oil ==> Late in Career (1 & 4)
Abstract-most-not Oil Paintings (5 & contrapositive of 1)

We'll look for one of these in the answer choices.

Answer Explanation:
Here we go! This matches one of the two conclusions anticipated. If you did not aniticpate this answer choice, the fifth statement in our summary talks about most abstract paintings, so this answer has potential. That statement connects most abstract paintings to being highly original. And while there are no statements with highly original as a sufficient condition, we can take the contrapositive of the first statement in our summary to get not Highly Original ==> not Oil Paintings.

When we have A-most-B; B ==> C, we can infer A-most-C. And that's what we have here, so this is our answer.

Key Takeaway: One trick to helping with quantifier statements is see how much overlap there is between the statements. Here, the link is "not Highly Original". In the fifth statement of our summary, we only talk about some of them, but we talk about all of them in the first contraposed statement. There has to be some overlap between some of a group and all of a group, so these two statements can be combined.

Diagramming and deducing with quantifiers is an advanced skill that takes some memorization of rules. Questions that call for this skill are relatively rare, but if you're looking to maximize your score, you'll need to learn this. It takes dedicated practice. Try diagramming things with "most" "some" and "all" relationships in the real world and figuring out what conclusions you can get, e.g. "Most of my friends are vegan" and "All vegans will not eat at barbecue restaurants." That leads you, of course, to the conclusion that "Most of my friends won't eat at barbecue restaurants."

Incorrect. We don't have enough information to infer this; importantly, we don't actually have any reason to believe any of her works were critically acclaimed! All we know is that most of her highly original oils weren't. Most doesn't exclude the possibility of all.