Information and Ideas · Reading & Writing
Inferences
A passage that stops mid-sentence, and four completions. The answer is the one the passage's stated premises actually force — a logical step, never a guess about the wider world.
46 questions in the bank · 10 easier · 24 medium · 12 harder · this domain is ≈26% of the section
What to watch for
Work from the premises, not from what seems sensible. If the text gives two facts, the answer is what follows from those two facts together; anything requiring outside knowledge is wrong.
How the question is worded
These are the actual stems used in the bank — the SAT reuses a small set of wordings, and recognising them saves time on test day.
- Which choice most logically completes the text?
- Based on the text, McClintock would most likely agree with which statement about the maize genome?
- Based on the text, Margulis would most likely agree with which statement about mitochondria?
- Based on the text, Milankovic would most likely agree with which statement about the timing of ice ages?
Worked examples
easyAlan Wilson's team collared wild cheetahs in Botswana with GPS and motion sens…
Alan Wilson's team collared wild cheetahs in Botswana with GPS and motion sensors and recorded every hunt they made over eighteen months. Cheetahs rely on explosive sprints that exhaust them within seconds, so a chase that lasts even half a minute usually ends with the prey escaping. Gazelles cannot match a cheetah's top speed, but they are far better at sustained running and rapid changes of direction. For a gazelle being hunted, then, the best strategy is likely to ______
Which choice most logically completes the text?
- A. prolong the chase while turning sharply and often.
- B. freeze in place until the cheetah loses interest.
- C. outrun the cheetah in a straight line at top speed.
- D. seek out other cheetahs to confuse its pursuer.
Answer: A. prolong the chase while turning sharply and often.
Explanation
The premises: cheetahs exhaust quickly and long chases fail; gazelles excel at endurance and turning. The strategy that follows is to stretch the chase and turn often — playing both stated advantages against the cheetah's stated weakness. A straight-line race plays into the cheetah's one strength.
mediumAnalytical bibliographers measure a book's untrimmed leaves to work out the si…
Analytical bibliographers measure a book's untrimmed leaves to work out the size of the sheet it was printed on, a method set out in Fredson Bowers's 1949 manual. Handmade paper shrinks slightly and unevenly as it dries, so two sheets from the same vat are never identical in size. Printers of luxury editions traditionally trimmed every page to a uniform rectangle after binding. Book historians who find an untrimmed "deckle edge" copy of an early luxury edition therefore treat it as especially valuable, because such a copy ______
Which choice most logically completes the text?
- A. proves that the printer could not afford the proper binding equipment of the period at all
- B. was very likely printed on modern machine-made paper rather than on handmade stock
- C. contains text that differs in places from the text found in the trimmed copies of it
- D. preserves physical evidence about the original sheets that trimming would have removed.
Answer: D. preserves physical evidence about the original sheets that trimming would have removed.
Explanation
Trimming erases the sheets' original, uneven edges; an untrimmed copy keeps them. The value follows from preserved evidence. A infers poverty from a practice described as traditional; C confuses page edges with text; B reverses the handmade context.
hardStephen Emlen raised indigo buntings under a planetarium sky in the 1960s, whe…
Stephen Emlen raised indigo buntings under a planetarium sky in the 1960s, where he controlled exactly which stars the birds saw and how the dome above them turned. Star navigation by night-migrating songbirds was long assumed to be learned by observing the rotating sky. In a classic line of experiments, birds raised in a planetarium whose artificial sky rotated around a false center point later oriented their migratory hops relative to that false center — not to the true North Star region. Birds raised with no sky at all failed to orient consistently in any direction. Together, the results indicate that these birds ______
Which choice most logically completes the text?
- A. inherit a tendency to use rotation to find a reference point but must learn which point
- B. cannot migrate successfully at all unless they are raised out of doors under a real sky
- C. rely primarily on landmarks rather than on the stars at any point in their migration
- D. are born already knowing the true location of the North Star region above them
Answer: A. inherit a tendency to use rotation to find a reference point but must learn which point
Explanation
The false-center birds used rotation but locked onto the wrong point (so the point is learned), while no-sky birds failed entirely (so sky experience is required, and the rotation-seeking tendency operates on whatever sky is given). A synthesizes both results. D is refuted by the false-center result; B overreaches (a planetarium sufficed); C contradicts the star-based design.