Logical Reasoning · Flaw

PrepTest 151 · Section 2 · Question 15

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

Step 1 · Pre-Question Guidance · read this first

Question type

Flaw

The one idea it tests

A total spread across containers says nothing about how it is spread. A few containers could hold most of it.

The basic logic

The patty: there are N times as many items as containers, and all items are in containers. Top bun: most containers hold more than one. The flaw: the average is more than one, but a few containers could hold a pile while most hold just one. This is a Team-to-Star Mix-Up: a fact about the whole group read as a fact about most members.

Tiny words that decide it

“all”
“most”
“times as many”

Playground logic

Kevin says there are three times as many stickers as lunchboxes, and every sticker is on a lunchbox, so most lunchboxes wear more than one sticker. But Kevin's own lunchbox might carry forty stickers, leaving everyone else with one each.

Step 2 · The kid story

Sticker Math

Kevin loves stickers. He also loves math, sort of. "Listen," he said at lunch. "Every sticker in this class is on a lunchbox. And there are three times as many stickers as lunchboxes. So most lunchboxes have more than one sticker." Lulu looked at her plain blue lunchbox with its one star. Tommy looked at his, one rocket. Nadia had one rainbow. Owen had one frog. Then everyone looked at Kevin's lunchbox. It was buried under dinosaurs, pizzas, planets, and one sticker that said "I heart pineapple pizza." Priya counted. "Kevin, you have about forty stickers. Everyone else has one." Kevin blinked. "So the average is three, but almost nobody has more than one?" "Exactly. A pile in one place can fake a crowd."

Step 3 · Try the model question

Kevin: Every sticker in our class is on a lunchbox. There are three times as many stickers as lunchboxes. So most lunchboxes in our class have more than one sticker.

Kevin's reasoning is open to which criticism?

Step 4 · The courtroom tale

The Parking Garage Promise

Judge Navarro read the brochure aloud. "All the cars in this garage belong to residents of the tower, and there are three times as many cars as residents. So most residents own more than one car." She looked at the developer's lawyer. "You used this to charge every resident a multi-car fee?" Mr. Whitfield rose for the tenants. "Your Honor, one resident, a collector, owns sixty cars. Nearly everyone else owns one, or none." The developer's lawyer squirmed. "But the average is three!" Mr. Whitfield smiled. "An average is not a majority. One big pile can hide a crowd of singles." The judge struck the fee.

Step 5 · Work the real question

Open PrepTest 151, Section 2, Question 15 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Find the ratio premise and the "most" conclusion. Ask whether the ratio could be true while the conclusion is false. Picture a lopsided spread: a few containers holding many, the rest holding one. If that scenario fits the premises, you found the flaw. Pick the choice that describes ignoring an uneven distribution. Reject Phantom Pieces: flaws the argument does not commit.