CruxStudy › Practice by skill › Information and Ideas
Inference questions practice
SAT, PSAT and ACT Information and Ideas · 65 questions in the bank
An inference question gives you a short passage ending in a blank and asks which choice most logically completes it. Nothing outside the passage is relevant, and nothing inside it should be extended further than it goes.
The skill is restraint. The correct answer is nearly always the most cautious option that the passage genuinely licenses.
How to answer these
- Read to the end and predict. Say what the passage is building toward before you look at the options.
- Find the logical hinge. Most of these turn on one connective or contrast in the final sentence. Identify what the passage has set up as needing completion.
- Test each option for support. Ask: which sentence in the passage licenses this? If you cannot point at one, it is not the answer.
- Prefer the weaker claim. Between two options the passage supports, the one that claims less is nearly always correct.
What the wrong answers look like
- The overreach. True in spirit but stated far more strongly than the passage supports. Watch for 'all', 'never', 'proves' and 'only'.
- The outside fact. Something you happen to know is true, which the passage never establishes.
- The reversal. Takes a relationship the passage describes and runs it backwards.
- The near miss. Supported by the passage but not the thing the final sentence was building toward.
Practice questions
Four real questions from the CruxStudy bank, with the keyed answer marked and the explanation behind a click so you can try them first.
Example 1Easier
Sea otters wrap themselves in strands of kelp before sleeping, which anchors them in place while they float. Researchers tracking a group of otters in a bay where the kelp had died off observed that the otters drifted long distances overnight and spent extra energy each morning swimming back to their feeding grounds. This suggests that ______
Which choice most logically completes the text?
- kelp provides sleeping otters with a benefit that is difficult to replace in its absence. correct
- otters in kelp-free bays eventually stop sleeping while floating.
- drifting overnight helps otters discover new feeding grounds.
- otters prefer bays without kelp because open water is easier to swim through.
Show the explanation
The completion has to say what the drifting observation shows, and because otters without kelp drift and then pay an energy cost to return, kelp provides a benefit that is difficult to replace in its absence. Drifting overnight helps otters discover new feeding grounds recasts the drifting as an advantage, but the text presents it only as a cost. Otters in kelp-free bays eventually stop sleeping while floating contradicts the observation that they do float and drift, and preferring bays without kelp reverses the preference the text describes.
Example 2Medium
Desert kangaroo rats rarely drink; they obtain water chiefly by metabolizing the seeds they eat. Their kidneys produce urine several times more concentrated than that of most mammals, and their nasal passages cool exhaled air, condensing moisture before it leaves the body. A laboratory population given unlimited access to water drank almost none of it. It follows that the species' water balance ______
Which choice most logically completes the text?
- depends less on the availability of drinking water than on mechanisms that conserve and generate water internally. correct
- would improve markedly if drinking water were available in the desert.
- is maintained in essentially the same way as that of most other mammals, whose kidneys produce urine several times more concentrated than a kangaroo rat's.
- requires more water in laboratory conditions than in the wild.
Show the explanation
The completion must follow from the whole set of observations, and because the animals generate water from food, conserve it aggressively, and ignore free water when offered, their balance depends on internal mechanisms rather than on drinking. Maintained in essentially the same way as most other mammals, whose kidneys produce more concentrated urine, not only erases the contrast the text draws but reverses it, since the text credits the kangaroo rat with the more concentrated urine. Would improve markedly if drinking water were available conflicts with the laboratory observation that they barely drank even when water was unlimited, and requires more water in laboratory conditions than in the wild is a comparison the text never makes.
Example 3Harder
Dynamic ticket pricing is often defended on the grounds that it moves money from resellers to artists: if the first sale already reflects what a fan is willing to pay, there is nothing left for a reseller to capture. Data from three recent stadium tours complicates that defense. On every one of them, resale listings appeared within minutes of the on-sale, and the median resale price sat above the highest price the primary seller had charged. This suggests that on those tours dynamic pricing ______
Which choice most logically completes the text?
- was set by the same algorithms that resale platforms use to price their listings.
- reduced the total number of tickets that were available to fans.
- did not push primary prices high enough to close the gap that resellers profit from. correct
- caused the artists involved to earn less than they had on their previous tours.
Show the explanation
The defense predicts no room for resellers, yet resale prices exceeded the top primary price, so the primary prices must have stayed below what fans would pay. The other choices introduce claims about algorithms, ticket supply, and artist earnings that the data described does not address.
Example 4Medium
When the city of Halverton opened its streetcar line in 1901, real estate advertisements began listing the distance to the nearest streetcar stop, and lots within a five-minute walk of a stop sold at a premium of nearly 20 percent. Developers soon petitioned the city to extend the line into unbuilt land they owned at the edge of town. The developers evidently believed that ______
Which choice most logically completes the text?
- the streetcar line was unprofitable on its existing downtown route.
- buyers preferred land at the edge of town regardless of transit access.
- streetcar access would raise the value of their outlying land enough to make seeking the extension worthwhile. correct
- the city already intended to extend the line to the edge of town, so that a petition would only confirm a decision taken back in 1901.
Show the explanation
The completion must supply the developers' motive, and having seen streetcar proximity command a 20 percent premium, owners of outlying land had an obvious financial reason to bring the line to it. The city already intended to extend the line, so that a petition would only confirm a decision taken back in 1901, contradicts the situation: developers do not petition for what is already planned, and the text describes no such plan. The line was unprofitable on its downtown route gives no reason to want it extended, and buyers preferred land at the edge of town regardless of transit access removes the very motive the petition implies.
Drill all 65 of them
Open the drill inside CruxStudy and it serves inference questions questions one at a time, with an explanation after every answer and your accuracy tracked. Free, no account.
Start a drill
See the lesson
Common questions
What does 'most logically completes the text' mean?
It asks for the conclusion the passage itself supports, using only the passage. Outside knowledge and plausible-sounding extensions are both wrong.
Why is the safest-sounding answer often right?
Because the passage is short and can only license so much. An option that claims more than the evidence supports fails even when it sounds more insightful.
How long should an inference question take?
Under a minute once you predict before reading the options. Most of the time lost on these goes to re-reading the choices instead of the passage.