Logical Reasoning · Inference

PrepTest 119 · Section 2 · Question 2

Phase 1 (your first ~400 questions): read the guidance, then answer. No clock.

Step 1 · Pre-Question Guidance · read this first

Question type

Inference / Must Be True

The one idea it tests

A 'could only have been done by someone who...' claim gives you a must-have requirement; whoever lacks it is ruled out, but having it does not prove anyone did it.

The basic logic

Sort the two works separately. For the first, the speaker only says a person could have done it, which leaves it open. For the second, the speaker names a requirement and says the person lacks it, so that person is out. Pack only that into your lunchbox: possible for one, ruled out for the other. Do not crown anyone else as the maker.

Tiny words that decide it

“could have”
“only”
“but”

Playground logic

Tommy could have drawn the silly doodles. But the map of the teachers' lounge could only have come from someone who had been inside, and Tommy never has. So the lunchbox holds this: the doodles might be Tommy's, the map is not.

Step 2 · The kid story

Who Drew the Lounge Map?

Two mystery drawings showed up on the class bulletin board. One was a page of goofy doodles of rocket-powered hamsters. The other was a detailed map of the teachers' lounge, right down to the secret cookie drawer. Marcus put on his detective hat. "Tommy could have drawn the doodles. He draws hamsters all the time. But that map? Only somebody who has been inside the lounge could draw it. Priya delivered the attendance folder in there last week. Tommy has never set foot inside." Lulu wrote it down carefully. "So the map is not Tommy's," she said. "The doodles might be." Marcus grinned. "So Priya drew the map!" Priya sipped her juice box. "Being inside is a must-have, not a proof. Lots of kids may have been in there."

Step 3 · Try the model question

Marcus: Tommy could have drawn the hamster doodles. But the lounge map could only have been drawn by someone who has been inside the lounge. Priya has been inside; Tommy has not.

If Marcus's statements are true, which one of these must also be true?

Step 4 · The courtroom tale

The Mystery Quilt

Two quilts won the county fair, and nobody signed the second one. "Your Honor," said Mr. Whitfield, "my client, Mr. Patel, may well have stitched the plain quilt. But the prize quilt uses a stitch taught only at the mountain sewing school. Ms. Dunn studied there. Mr. Patel never did." The other lawyer jumped up. "Then Ms. Dunn made the prize quilt!" The judge raised one eyebrow. "Slow down. Going to that school is a requirement, not a confession. Plenty of people may have studied there. What I can conclude is narrow: Mr. Patel did not make the prize quilt, and the plain one might be his." Mr. Whitfield bowed. "That is all we ask."

Step 5 · Work the real question

Open PrepTest 119, Section 2, Question 2 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Split the stimulus into two separate claims, one per kind of work. Label the first as merely possible for the person named. Turn the 'could only' statement into a requirement, then check whether the person meets it. Predict: possible for one, ruled out for the other. Reject answers that name a new author with certainty, because meeting a requirement proves nothing, and reject answers that go beyond 'could have' into 'did'.