Reading Comprehension · Science
PrepTest 149 · Section 2 · Passage 2
Questions 6–12
Before you start
Open PrepTest 149, Section 2 in your official copy from LSAC and read the passage for Questions 6–12, using the structure guide below. The passage is not reprinted here.
Structure guide
- P1: opens with a vivid everyday analogy
- P2: applies the analogy to the main subject, gives an example, and states the puzzle of improbability
- P3: presents some experts' proposed explanation for the puzzle
- P4: questions how special the case really is and names where the puzzle comes from
- P5: describes the usual test method, criticizes its limit, and reports the author's own different results
- P6: asks whether the author's results undercut the explanation from P3 and gives two reasons they need not
Step 2 · The kid passage
Grandma's Perfect Lemon Cake
Owen's marble run is a wonder. The marble rolls past a dozen spots where one tiny bump would knock it off the track. Yet it lands in the cup every time.
Grandma's lemon cake is like that marble. Change any one amount even a little and, it seems, the cake flops. With one more spoon of baking soda, it would taste like soap. So the perfect cake looks almost too lucky to exist.
Some bakers explain the luck this way: Grandma baked hundreds of test cakes with random amounts. Nearly all flopped. With that many tries, one great cake was bound to show up.
But how special is the recipe, really? The idea that it is perfectly tuned comes mostly from the fact that nobody has found another great version.
The usual test is to change one amount and keep every other amount the same. Then the baker "bakes it out," following the batch all the way to the finished cake to see what goes wrong. But why change only one thing? Priya and I changed several amounts at once, more sugar with less flour and an extra egg, and we found many cakes that were very different from Grandma's and still delicious.
Some bakers point to the perfect recipe as a sign of the hundreds of test cakes. Do our results sink the test-cake idea? Not necessarily. There are two reasons. To begin, Grandma's old notebooks hint that she did bake many trial cakes. Second, the test-cake idea may help solve other kitchen puzzles, like why her cookies are so good too.
Step 4 · The courtroom tale
The Case of the One-Try Lock
The prosecutor pointed at the defendant. "Your Honor, she opened the club's lock on her first try. That is too unlikely. She must have known the code." Mr. Whitfield rose. "How unlikely, though? My expert tested the lock by turning one dial at a time, as usual, and it seemed picky. Then she turned several dials together and found dozens of settings that open it." The judge raised an eyebrow. "So the lock is not so picky after all." "Exactly," said Mr. Whitfield. "And I will not rule out that many members simply try codes all day. That idea may still be true. It just is not the only way to explain an open lock."