Logical Reasoning · Necessary Assumption

PrepTest 130 · Section 4 · Question 21

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

Step 1 · Pre-Question Guidance · read this first

Question type

Necessary Assumption

The one idea it tests

Knowing about the rare winners must actually change at least some people's guesses about their own chances.

The basic logic

The evidence: winning is rare, winners get noticed, and people notice what gets noticed. The conclusion: many people overrate their own chances. The missing link is that noticing winners leads some people to misjudge their own odds. Pull that plank and the argument falls.

Tiny words that decide it

“likely”
“at least some”
“many”

Playground logic

Star of the Week is rarely you, but the winners get a giant hallway poster everyone walks past. The top bun says many kids overrate their chances. The secret sauce: seeing those posters makes at least some kids guess too high about themselves.

Step 2 · The kid story

The Star of the Week Poster

Every Monday, Ms. Rivera pulls one name out of a hat for Star of the Week. With three hundred kids in the school, your chance is tiny. But the winner gets a giant poster in the main hallway with glitter and a gold star. Everyone walks past it every day. Marcus made a bold claim. "Since everybody sees the posters, lots of kids must think they will be picked any week now." Priya held up her juice box. "Pull the plank test. Imagine that seeing the posters never changed anybody's guess about their own chances. Then your argument has nothing left." Marcus thought. "So I am assuming that seeing the winners makes at least some kids guess too high about themselves." "Exactly," said Priya. Tommy was already practicing his poster pose.

Step 3 · Try the model question

The chance of being picked Star of the Week is very small. But winners get a giant poster in the hallway, and nearly every kid walks past it daily. So many kids probably think they are much more likely to be picked than they are.

Marcus's argument requires which assumption?

Step 4 · The courtroom tale

The Raffle Billboard

At a hearing about a charity raffle, Ms. Hale argued for the raffle company. "The odds are tiny, Your Honor, but winners appear on a huge billboard downtown. Everyone sees it. So many folks surely think they will win." Mr. Whitfield tugged his suspenders. "Your Honor, my colleague skips a step. Seeing a billboard is one thing. Changing your guess about your own chances is another. If the billboard never changed a single person's guess, her whole point vanishes." The judge nodded. "So the argument needs this: seeing winners causes a few people, at minimum, to misjudge their own odds. Ms. Hale, that is a plank you cannot pull."

Step 5 · Work the real question

Open PrepTest 130, Section 4, Question 21 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Lay out the burger: background odds, the evidence about attention and awareness, and the conclusion about people's guesses. Find the gap between being aware of winners and misjudging one's own chances. Use the Pull the Plank test on each choice: negate it and see whether the argument collapses. Prefer a modest 'at least some' link over choices about 'most' people or about what would happen without the attention.