Logical Reasoning · Inference

PrepTest 152 · Section 2 · Question 24

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 False)

The one idea it tests

Find the choice that crashes into a rule the passage states as a flat 'impossible'.

The basic logic

Sort the statements: which are 'usually' and which are absolute. A 'usually' claim can have exceptions, so a choice that goes against it can still be true. An 'impossible' claim allows no exceptions. The must-be-false choice says the impossible thing happens, and often.

Tiny words that decide it

“usually”
“impossible”
“most”
“however”

Playground logic

Tommy's lunch trades usually go through, and a sweetener usually saves a shaky trade, but a sweetener is impossible when the trade involves someone's lucky item. So the claim that most lucky-item trades go through thanks to a sweetener has to be false.

Step 2 · The kid story

The Lunch Trade Rules

Tommy runs the busiest lunch-trade table in the fourth grade. Lulu keeps the records. "Here's what my clipboard says," Lulu explained to Kevin. "When Tommy offers a trade, most kids are ready to say yes. If a trade looks like it won't happen, Tommy can usually fix it with a sweetener, like throwing in a pretzel. But a sweetener never works when the trade involves somebody's lucky item. Nobody gives up a lucky item for a pretzel." Kevin held up his lucky dinosaur eraser. "So could I trade this for a cupcake plus a pretzel?" "Not through a sweetener," said Lulu. "Sweeteners can't happen on lucky items. Ever." Kevin hugged his eraser. "Good. I wasn't going to anyway." Tommy sighed and ate the pretzel himself.

Step 3 · Try the model question

Lulu: When Tommy offers a lunch trade, most kids are usually ready to accept. And when a trade at first looks unlikely, a sweetener deal usually makes it work. But sweetener deals are impossible when the trade involves someone's lucky item.

Suppose everything Lulu says is true. Which choice is impossible?

Step 4 · The courtroom tale

The Case of the Garage Sale Haggle

The judge read the town clerk's report. "At garage sales, most buyers pay the sticker price. When a buyer balks, haggling usually saves the sale. But haggling is impossible on family heirlooms, by town rule." The defense lawyer stood. "Your Honor, my client says most heirlooms in town were sold thanks to haggling." Mr. Whitfield rose, smoothing his suspenders. "Then your client says something that cannot be true. If haggling is impossible on heirlooms, no heirloom was sold by haggling, much less most of them." The judge nodded. "The 'usually' parts bend. The 'impossible' part does not. Next witness."

Step 5 · Work the real question

Open PrepTest 152, Section 2, Question 24 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Mark each statement as 'usually' or absolute. For a must-be-false question, the right choice must clash with the facts in every possible world, so it almost always collides with an absolute rule. Test each choice: can you imagine a world where all the statements hold and this choice holds too? If yes, toss it. Keep the one that has the forbidden thing happening.