PrepTest 132

Incorrect. As we stated in our Anticipation, there are no inferences that can be drawn by combining statements with the most statements, so we should defer/eliminate this answer after the first word.

Incorrect. Tropical fish AND Exotic birds → Gerbils. We know that the stores selling fish and no birds sell gerbils, but this answer doesn't line up with that in that it discusses stores selling exotic birds.

Incorrect. As we stated in our Anticipation, there are no inferences that can be drawn by combining statements with the most statements, so we should defer/eliminate this answer after the first word.

Correct. Argument or Facts:
Facts

Question Type:
Must Be True

Stimulus Summary:

(1) Pet store-most-Exotic birds
(2) Exotic birds-most-Tropical fish
(3) Tropical fish AND not Exotic birds → Gerbils
(4) Independently owned → not Gerbils

Answer Anticipation:
It's rare that we get conjunctions (AND) and quantifiers in the same stimulus, but here we are! It's time to get our hands dirty and figure out this conditional logic so we can make an inference and get to our answer.

The easiest place to start here is with those two conditionals—they chain together if we take the contrapositive of either of them, so let's do that for statement #3 and then combine them, remember AND negates to OR:

Independently owned → not Gerbils → not Tropical fish OR Exotic birds

Now we need to look at those quantified statements. First consideration—can they be combined? Two most statements can be combined, but only when the initial term is shared between them—they don't chain together, as this set of statements would have you do. So there's no inference to be made from statements #1 and #2.

The second consideration is whether they could be combined with statements #3/#4. However, since the overlapping terms are part of an OR statement, neither is guaranteed. That means we're not going to be able to combine these statements.

This tells us two very important pieces of information:

(1) The correct answer will derive from our conditional chain or its contrapositive, which we'll write out now:

Independently owned → not Gerbils → not Tropical fish OR Exotic birds
Tropical fish AND not Exotic birds → Gerbils → not Independently owned

(2) Since we can't draw any inferences with those most statements, any most answer will almost certainly be incorrect. That should allow us to make some quick eliminations!

Answer Explanation:
Independently owned → not Tropical fish OR Exotic Birds. Note our diagram here, as this is a tough one to crack! However, there are two ways to deal with "No" as a conditional indicator—we decided to use it as an introduction for the sufficient condition, but then it negates the other condition. Negating "Tropical fish AND not Exotic birds" as this answer states gives you "not Tropical fish OR Exotic birds"—don't forget to negate the linkage! That matches the conditional chain from our Anticipation, so it's the correct answer.

Key Takeaway:
Sometimes, knowing when you can't make an inference in a question that features conditionals and quantified statements is as important as knowing when you can. Spotting the inability to use those quantified statements here made our answer choice work a lot faster—we were able to eliminate two answers that had quantifiers.

Incorrect. Independently owned AND not Tropical fish → Exotic birds. The conditional chain establishes that independently owned pet stores either don't sell tropical fish or do sell exotic birds. Thus, this sufficient condition establishing an independent store that doesn't sell tropical fish satisfied the necessary condition of the rule from the stimulus, and no conclusion can therefore be drawn about the other element in that condition.