Logical Reasoning · Paradox

PrepTest 140 · Section 2 · Question 7

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

Step 1 · Pre-Question Guidance · read this first

Question type

Paradox

The one idea it tests

When one input cost jumps, a product's price rises by roughly the share of its cost that input makes up.

The basic logic

Two products both use the same input, yet one barely gets pricier while the other nearly doubles. Look for an answer that shows the input is a small slice of one product's cost and most of the other's. That shakes hands with both sides.

Tiny words that decide it

“whereas”
“most”
“only”

Playground logic

If paper doubles in price, Aunt Rosa's comic books go up a little, but the paper-airplane kits nearly double. The handshake: the comics' cost is mostly drawing and printing work, while the kits are almost all paper.

Step 2 · The kid story

Aunt Rosa's Craft Shop

Aunt Rosa runs a little craft shop. One day she frowned at a letter. 'Paper is about to double in price,' she said. 'My comic books will cost a little more, maybe a dime. But the paper-airplane kits? Those will almost double.' Marcus was puzzled. 'They're both made of paper! They should go up the same!' Priya thought it through. 'What do you pay for, when you make each one?' Aunt Rosa explained: 'For comics, I mostly pay the artist and the printer. The paper is cheap next to that. For the airplane kits, the paper is nearly the whole cost.' Priya nodded. 'Then doubling paper barely touches the comics but hammers the kits.' Kevin built a pineapple-shaped paper airplane. It did not fly.

Step 3 · Try the model question

If paper doubles in price, Aunt Rosa's comic books will cost only slightly more, but her paper-airplane kits will nearly double in price.

Which of these, if true, best explains the difference?

Step 4 · The courtroom tale

The Rubber Shortage Hearing

When rubber prices doubled, a toy maker raised the price of rubber balls almost twofold, but bicycles rose only a little. A customer sued, claiming unfair pricing. The toy maker's lawyer explained, 'Your Honor, a rubber ball is nearly all rubber. A bicycle is mostly steel, gears and assembly labor. The tires are a small slice.' Judge Akin nodded. 'So the same cost jump hits each product according to how much of it is rubber. Both prices make sense.' Mr. Whitfield, representing nobody that day, approved anyway.

Step 5 · Work the real question

Open PrepTest 140, Section 2, Question 7 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

State the puzzle in one line: the same input change produces very different price changes for two products. Then look for an answer that speaks to both products and explains the gap. The winner usually describes how much each product depends on the input. Cut answers that talk about only one product, or about price levels, buyers, or sellers without touching cost shares.