Free digital SAT practice questions, with every answer explained

B. Correct. Years of patient watching led to a discovery that made her famous: her patience paid off, so it was rewarded.

1. Cover the choices and predict a word from the clue: years of watching, then a famous discovery. Something like "paid off".
2. Only "rewarded" matches.

Why the others are wrong: A Nothing in the text suggests anyone doubted her patience; the discovery is presented as its payoff. C The discovery made her famous, so her patience was revealed, not hidden. D Her patience did not run out; it produced a discovery. "Exhausted" points the wrong way.

A. Correct. "Curiously" flags a surprising fact (the third heart stops while swimming), and the sentence connects it to crawling rather than swimming.

1. Find what the sentence adds: a surprising detail ("Curiously") and a possible consequence ("which may be one reason").

Why the others are wrong: B The third sentence builds on the first sentence's claim about three hearts; it does not dispute it. C The gills are covered in the second sentence, not the third. D No other animals are mentioned in the text.

A. Correct. Text 2 values students reading more pages, so it shares the goal, but it says a required list "can backfire" and that choice works better.

1. Find where the texts agree (reading over the summer is good) and where they differ (fixed list or free choice).

Why the others are wrong: B Text 2 praises students reading more over the summer; it does not want them to stop. C Text 2 says a fixed list can backfire, the opposite of calling it most effective. D Text 2 never discusses whether skills decline; it is about how much students read.

A. Correct. The text moves from Mendel's counting, to his conclusion about separate units of heredity, to its being ignored until about 1900.

1. The main idea covers the whole text: what he did, what he concluded, and what happened to his work.

Why the others are wrong: B The text is about breeding peas to study traits, not growing them for food, and makes no claim about being first. C The text never compares peas with other plants. D Researchers in 1900 reached similar results, which supported Mendel rather than proving him wrong.

A. Correct. Buds are a sign of spring, and "Yet" turns from the frozen scene to them.

1. The claim has two parts: winter, and a sign of spring. Pick the line with the sign of spring.

Why the others are wrong: B These lines describe the frozen fields, sky and creek, with no sign of spring. C A frozen creek is a sign of winter, not of spring. D This line stresses that the trees look dead, the opposite of a sign of new growth.

A. Correct. The text gives one diet trait (water from seeds) and one behavior (resting in cool, humid burrows); "taken together" asks for both.

1. "Taken together" means the ending must combine the points made before it: seeds (diet) and burrows (behavior).

Why the others are wrong: B Nothing in the text says what kangaroo rats would do if water were easy to find. C The text does not compare desert seeds with other seeds. D They spend the hottest part of the day in burrows, which implies they leave them at other times.

A. Correct. It names the almanacs and what was in them: his calculations, eclipse predictions, and sunrise and sunset times.

1. Read the goal first, then pick the choice that does exactly that: here, the contents of the almanacs.

Why the others are wrong: B This is about how he learned astronomy, not what the almanacs contained. C This mentions neither the almanacs nor their contents. D This says when he began publishing but not what the almanacs contained.

D. Correct. Sonar came after the rope method and improved on it, so a time transition fits.

1. Name the relationship between the sentences first (here: an earlier method, then a later one), then match the transition.

Why the others are wrong: A Sonar is a different, better method, not one like weighted ropes. B Sonar is not an example of rope measurement. C Sonar was not caused by the scattered rope measurements.

C. Correct. A colon follows a complete clause ("The museum's newest exhibit features three objects") and introduces the list that explains it.

1. Is what comes before the blank a complete sentence, and does what follows explain it? Then a colon works.

Why the others are wrong: A A comma here makes it unclear that the list names the three objects. B A semicolon must join two complete clauses, and the list is not a clause. D With no punctuation, "objects a carved wooden mask" runs together.

D. Correct. The subject is "collection", which is singular, so it takes "is". "Of letters written by the explorer's crew" only describes it.

1. Cross out the describing phrase between the subject and the verb, then match the verb to "collection".

Why the others are wrong: A "Are" is plural; the subject is the singular "collection", not "letters". B "Were" is plural, and "now" calls for the present tense. C "Have been" is plural; the singular subject needs "has".

A. Correct. So C(d) = 70d + 45.

1. The per-day rate, $70, is the slope: it multiplies the number of days.
2. The one-time fee, $45, is the starting amount: the constant term.
3. So C(d) = 70d + 45.

Why the others are wrong: B This adds the fee into the rate, so the fee would grow with every day. It is paid only once. C This charges the one-time fee every day. The fee is paid once, so it is the constant term; the per-day rate multiplies d. D Multiplying out gives 70d + 3150: the fee would be $3150, not $45.

C. Correct. Here 5 multiplies d, so it is the rate; 80 is the value at d = 0.

1. In y = b + mx, the constant b is the value when x = 0 and m is the change for each unit of x.
2. Here 5 multiplies d, so it is the rate; 80 is the value at d = 0.

Why the others are wrong: A That would be the value of H at a particular time, found by substituting. The number itself is the starting value. B That describes the rate, 5. The number 80 is the value when d = 0. D 80 is not a time. It is a starting amount.

C. Correct. So 4a + 6b ≤ 95.

1. Money spent on tickets for students: 4a. On tickets for adults: 6b.
2. "At most $95" means the total is less than or equal to 95.
3. So 4a + 6b ≤ 95.

Why the others are wrong: A The prices are switched: each of the tickets for students (a) costs $4. B This limits the number of items, not the money spent. Each item has to be multiplied by its price. D "At most" means the total cannot go over the budget, so it is ≤, not ≥.

A. Correct. Last: −9 × −9 = 81.

1. First: 5x × 4x = 20x².
2. Outer plus inner: −45x + −36x = −81x.
3. Last: −9 × −9 = 81.

Why the others are wrong: B One of the middle products has the wrong sign. Check each sign as you multiply. C This multiplies only the first terms and the last terms. The outer and inner products make the middle term. D The constant term is the product of the last terms, −9 × −9 = 81, not their sum.