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SAT Reading and Writing Practice
Inferences

Draw logical conclusions that are strongly supported by, but not explicitly stated in, a passage.

19 original inferences questions in the SAT Ranker bank, with instant scoring and an Elo-based rank once you sign up. Below are a few free samples with full explanations.

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Sample question 1 · medium

Communities of tube worms, crabs, and shrimp thrive around hydrothermal vents on the ocean floor, thousands of meters below any sunlight. Chemosynthetic bacteria there convert vent chemicals into energy, forming the base of a food web entirely independent of photosynthesis.

Which inference is best supported by the passage?

Hydrothermal vent ecosystems are less complex than sunlit ecosystems.
Life at hydrothermal vents does not depend on energy derived from sunlight.
Chemosynthetic bacteria are found only near hydrothermal vents.
Tube worms and crabs are the primary chemosynthetic organisms at vents.

The passage explains the food web there runs on chemosynthesis from vent chemicals rather than photosynthesis, supporting the inference that this ecosystem's energy doesn't depend on sunlight.

Sample question 2 · hard

Researchers studying urban foxes noticed that populations in cities with more pedestrian-only zones displayed less nocturnal activity than those in cities dominated by vehicle traffic, foraging comfortably even in daylight hours in the former.

Which inference is best supported by the passage?

Urban foxes cannot survive in cities with heavy vehicle traffic.
Foxes' activity patterns may be influenced by their perceived risk from vehicle traffic rather than daylight itself.
Foxes exclusively live in pedestrian zones.
Nocturnal behavior in foxes is entirely genetic and unaffected by environment.

The contrast between fox behavior in pedestrian versus vehicle-heavy areas suggests traffic-related risk, not daylight itself, shapes when foxes are active, supporting the second choice.

Sample question 3 · hard

A widely used open-source encryption library was found to contain a critical vulnerability that had gone unnoticed for over a decade, despite being freely available for anyone to inspect. The bug was eventually discovered not by a large security firm but by a single volunteer auditing the code in his spare time.

Which inference is best supported by the passage?

Open availability of source code guarantees that vulnerabilities will be found quickly.
Open availability of code does not by itself ensure that flaws are promptly discovered.
Only large security firms are capable of finding critical vulnerabilities.
The volunteer intentionally introduced the vulnerability.

The vulnerability existed for over a decade despite being open to inspection, showing that mere availability of code doesn't guarantee prompt discovery of flaws.

Sample question 4 · medium

Octopuses can alter both the color and the texture of their skin within a fraction of a second, matching not just the hue but the physical bumpiness of nearby coral or rock, despite octopuses themselves being colorblind.

Which inference is best supported by the passage?

Octopuses must be able to see color in order to camouflage effectively.
Octopuses can achieve effective camouflage through means other than perceiving color directly.
Camouflage in octopuses is limited to changes in texture only.
Octopuses camouflage more slowly than most other animals.

Since the passage states octopuses are colorblind yet still match color and texture, it supports the inference that their camouflage doesn't depend on directly perceiving color.

Sample question 5 · hard

Two nearby vineyards planted the same grape variety in the same year. The first, on a south-facing slope, consistently ripens its grapes about two weeks earlier than the second, which lies on a shaded valley floor, even though the two sites receive nearly identical rainfall.

Which choice most logically completes the text?

differences in sunlight exposure likely account for the difference in ripening times.
the second vineyard uses a different grape variety than the first.
rainfall is the main factor determining when grapes ripen.
the first vineyard produces higher-quality wine than the second.

With the same variety, year, and rainfall, the remaining difference is the sites — a sunny south-facing slope versus a shaded valley floor — so sunlight is the likely cause of the earlier ripening. The passage rules out variety and rainfall as the difference and says nothing about wine quality.

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SAT Reading and Writing skills
Words in ContextCentral Ideas and DetailsCommand of EvidenceText Structure and PurposeCross-Text ConnectionsRhetorical SynthesisTransitionsBoundariesForm, Structure, and Sense