Reading Comprehension · Science
PrepTest 152 · Section 3 · Passage 4
Questions 20–26
Before you start
Open PrepTest 152, Section 3 in your official copy from LSAC and read the passage for Questions 20–26, using the structure guide below. The passage is not reprinted here.
Structure guide
- P1: gives background, the standard picture of how something began and changed
- P2: introduces two researchers' claim that the starting event was not one of a kind, resting on a wider framework
- P3: explains a general principle the researchers began from, with an everyday illustration
- P4: names a puzzle the principle raises and presents the researchers' new move
- P5: cites other researchers' suggestion that the pair builds on
- P6: concludes by showing how, on this view, the puzzle goes away
Step 2 · The kid passage
The Mystery of the Rainbow Tower
Everyone at Maple School agrees on how the art room's brick bin began: as one tiny tower, every brick sorted by color, which has been getting more jumbled every year since.
Nadia and Owen say that tower was not a one-time thing. Towers like it pop up again and again. Their idea depends on something the custodian told them: our art-room bin is just one scoop taken from the district's Mega Bin, a warehouse full of bricks, including the parts we will never see from our scoop.
Nadia and Owen first wondered why bricks only ever get messier. The reason is simple: there are far more jumbled arrangements than sorted ones. Shuffle a sorted deck of cards and you almost never get it back in order. So random bumping nearly always means more mess.
But then why did the bin start as a sorted tower? A start that tidy is wildly unlikely if things are random. Nadia and Owen's new idea is that the usual starting state is a gray, quiet jumble.
Lulu noticed that the Mega Bin is never perfectly still: delivery trucks give it constant tiny jiggles, and now and then a jiggle snaps a small patch of bricks into color order. Nadia and Owen think our tower was one of those patches.
So a sorted tower, which looks impossible on its own, is not so strange in a bin as big as a warehouse. It has probably happened many times.
Step 4 · The courtroom tale
The Case of the Lucky Coin
A carnival owner was accused of rigging a coin toss after one booth flipped heads twenty times in a row. "Twenty heads is nearly impossible!" said the prosecutor. Mr. Whitfield called a math teacher to the stand. "Your Honor," she said calmly, "for one booth on one afternoon, yes, that streak is wildly unlikely. But this fair runs ten thousand booths every day, all summer, year after year. In a crowd of flips that huge, a long streak somewhere is expected. It has likely happened before." Mr. Whitfield nodded. "So the streak only looks strange when you look at it alone." The judge agreed: the witness had explained why a rare event becomes ordinary in a big enough setting. Case dismissed.