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The real test, rehearsed.

98 questions across four modules, in the digital SAT’s order and on its timing, with a highlighter, a question map and a timer you can see.

A Peakscor full-length test in progress: Reading and Writing, Test A, Module 1 of 4, question 7 of 27, with the passage, four answer choices, a highlighter, a 24:18 timer and Flag, Back and Next buttons.

How it works

One run a day. One skill at a time.

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    Play the Daily.

    A quick run with three hearts. String right answers together and the questions get harder and the points multiply.

  2. 2

    Miss one, learn why.

    Every question is tagged by domain and skill, and every answer comes with an explanation.

  3. 3

    Drill that skill.

    Practice any single skill at any difficulty, or just the questions you got wrong.

  4. 4

    Beat your best.

    Come back tomorrow and climb. Progress shows your accuracy and your strongest skills.

Built around the real SAT blueprint.

Every question is tagged by section, domain, skill and difficulty, so you can practice exactly what you need. Full tests run like test day: two Reading & Writing modules, a break, then two Math modules.

Free daily practice

12 easy, 12 medium and 12 hard questions free every day, each with a full explanation. Filter by section, domain, skill and difficulty. Resets at midnight.

Real SAT timing

Take any test on official timing, extended 1.5× time, or untimed to focus purely on accuracy.

Adaptive full-length tests

Four modules in official order. The second module of each section adapts to how you did on the first.

Vocabulary

1,023 essential SAT words. Browse the list, flip flashcards, or quiz yourself.

Your progress

Accuracy across daily practice and full tests, your strongest skills, and the ones that need the most help.

Games

PEAK Survivor, Hole and Peak Defense: three games powered by SAT practice questions.

Explanations

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Not just the right letter: how to get there, and why the tempting answer is wrong.

MathProblem-Solving and Data AnalysisHard

A store raises the price of a jacket by 20%. Later, it lowers the new price by 20%. The final price is what percent of the original price?

A80%
B96%Correct
C100%The trap
D104%

Check with $100: $100then$120then$96

  1. Turn each change into a multiplier.

    Up 20% means × 1.20. Down 20% means × 0.80.

  2. Apply them in order.

    1.20 × 0.80 = 0.96

  3. Read the answer.

    The final price is 96% of the original. That’s B.

  4. Why not 100%?

    The 20% cut is taken from the higher price, so it removes more than the 20% increase added.

Test day

What test day looks like.

Every Peakscor full test follows this order. In the standard tests, the second module of each section adapts to how you did on the first.

  1. Reading & Writing · Module 1

    27 questions32 min

  2. Reading & Writing · Module 2

    27 questions32 min

    Adapts to how you did on Module 1.

  3. Break

    10 min

  4. Math · Module 1

    22 questions35 min

  5. Math · Module 2

    22 questions35 min

    Adapts to how you did on Module 1.

98 questions · 2 hr 14 min of testing, plus the break

Peakscor by the numbers

  • 36free practice questions every day
  • 98questions in every full-length test
  • 1,023SAT vocabulary words
  • 1.5×extended-time option on every test

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  • Full-length Test A and Challenge Test 1
  • All 1,023 vocabulary words: browse, flashcards and quiz
Start free daily practice

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FAQ

Questions, answered.

The Daily, plus 36 practice questions every day: 12 easy, 12 medium and 12 hard, each with a full explanation. Full-length Test A, Challenge Test 1 and all 1,023 vocabulary words are free too. No card needed.

Pro is $20 a month or $200 a year: unlimited practice with no daily limit, plus every full-length test and Challenge test. Peak is $29 a month or $280 a year: everything in Pro, plus the full Learn course and Peak Plan. Cancel anytime from your account.

98 questions across four modules, in the digital SAT’s order: Reading & Writing Module 1 and Module 2 (27 questions each), a 10-minute break, then Math Module 1 and Module 2 (22 questions each). On official timing that’s 2 hr 14 min of testing. You get estimated section scores and a total at the end.

Yes. In the standard full-length tests, Module 2 of each section is the harder version if you get 60% or more of Module 1 right, and the easier version if you don’t. Challenge tests use the hardest material throughout.

Official timing, extended 1.5× time, or untimed, on every test, including the free ones. Extended time allows 48 minutes for each Reading & Writing module and about 52 for each Math module. Untimed removes the clock so you can focus on accuracy.

A quick run with three hearts. Each right answer builds your streak: the questions get harder as it grows, and your points multiply (×2 from three in a row, ×3 from six). A miss costs a heart and drops you back to easy. Best is your longest streak.

Every day at midnight. You get a fresh 12 easy, 12 medium and 12 hard.

No. Peakscor is an independent SAT practice tool, not affiliated with the College Board. Scores shown are estimates.

Your next point starts today.

Free, no card.

Probability and conditional probability · Lesson 4

From a probability to an expected count

A probability also tells you what to expect in a larger group. Expected number = probability × size of the group. If the probability that a phone in a shipment is defective is 0.02, a shipment of 1,500 phones should have about 0.02×1500=300.02 \times 1500 = 30 defective phones.

From a sample. When a random sample is a fair picture of a larger group, the fraction in the sample works as the probability. Find the fraction for the group the question names, then multiply by the size of that group in the population.

Working backward. If you know a count and its probability, divide. If 10 red cards make the probability of drawing red 29\frac{2}{9}, the deck has 10÷29=4510 \div \frac{2}{9} = 45 cards. Check: 1045=29\frac{10}{45} = \frac{2}{9}.

Percents work the same way once you change them to decimals: 2.5% is 0.025, not 0.25. Estimate first to catch a slipped decimal point: 1% of 800 is 8, so 2.5% of 800 is two and a half times that, 20.

An expected count is an estimate, which is why stems say about how many or would be expected. Real results vary, but the expected count is the number the question wants.

Worked example Easy

A factory finds that the probability that a light bulb it makes is defective is 0.015.

Based on this probability, about how many defective bulbs would be expected in a batch of 4,000 bulbs?

  1. 6060Answer
  2. 600600
  3. 3,9403{,}940
  4. 6,0006{,}000

How to solve it

  1. Expected count = probability × number of bulbs.
  2. 0.015×4000=600.015 \times 4000 = 60.
  3. Sense check: 0.015 is 1.5%, and 1% of 4,000 is 40, so 1.5% is one and a half times that, 60.

Why each choice is right or wrong

  • A. Correct. 0.015×4000=600.015 \times 4000 = 60 bulbs are expected to be defective.
  • B. Incorrect. This uses 0.15: 0.15×4000=6000.15 \times 4000 = 600. But 0.015 is 1.5%, not 15%.
  • C. Incorrect. 4000−60=39404000 - 60 = 3940 is the number of bulbs expected not to be defective.
  • D. Incorrect. This multiplies by 1.5, the percent form of 0.015, instead of by 0.015 itself: 1.5×4000=60001.5 \times 4000 = 6000. That is more bulbs than the whole batch holds.

Worked example Medium

A random sample of 200 juniors and seniors at a city's high schools was asked whether they have a part-time job. The results are shown.

GradeHas a jobNo jobTotal
Junior3090120
Senior364480
Total66134200

There are 2,000 seniors at the city's high schools. Based on the sample, about how many of these seniors have a part-time job?

  1. 360360
  2. 660660
  3. 900900Answer
  4. 1,1001{,}100

How to solve it

  1. The question is about seniors, so use the Senior row: 36 of the 80 sampled seniors have a job.
  2. That fraction is 3680=0.45\frac{36}{80} = 0.45.
  3. Expected count: 0.45×2000=9000.45 \times 2000 = 900.

Why each choice is right or wrong

  • A. Incorrect. This divides 36 by the whole sample, 200, which gives 0.18, and 0.18×2000=3600.18 \times 2000 = 360. The question is about seniors only, so divide by the 80 seniors.
  • B. Incorrect. This uses everyone in the sample with a job, juniors included: 66200=0.33\frac{66}{200} = 0.33, and 0.33×2000=6600.33 \times 2000 = 660.
  • C. Correct. In the sample, 3680=0.45\frac{36}{80} = 0.45 of the seniors have a job, and 0.45×2000=9000.45 \times 2000 = 900.
  • D. Incorrect. This uses the seniors with no job: 4480=0.55\frac{44}{80} = 0.55, and 0.55×2000=11000.55 \times 2000 = 1100.

Trap Using the whole sample's rate for one group

When the question asks about one group, the rate must come from that group in the sample: its cell divided by its row or column total. The whole sample's rate and the cell over the grand total both give numbers that can show up as choices.

Trap Slipping a decimal place

Small probabilities are easy to misread. 2.5% is 0.025, and 0.25 is 25%. Make a quick estimate with 1% before you pick, and choose the answer that fits it.

Desmos When Desmos is faster

For a messy product, typing is faster and safer than working by hand. Type 0.015*4000 and Desmos shows the result, 60, next to the expression. The asterisk appears as a multiplication dot.

For a rate from a table, type the fraction and then the multiplication, such as 36/802000. Desmos turns the slash into a fraction bar and keeps typing in the denominator, so press the right arrow key after 80 before you type 2000. Otherwise you get 3680⋅2000\frac{36}{80 \cdot 2000}.

With clean numbers, such as 14\frac{1}{4} of 200, mental math is quicker. And choosing the right fraction is still your job: Desmos multiplies the wrong rate just as readily as the right one.

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Full-length tests

Each test mirrors the digital SAT: 98 questions across four modules, 2 hr 14 min on official timing.

A little harder than the real SAT. These tests can run slightly tougher than test day, which makes them good practice: if you can handle these, the real one should feel easier. No question appears in more than one test, Challenge Tests included.

Challenge Tests Hardest of the hardest

Same 98-question format, but every question is drawn from the toughest SAT material: Challenging-tier math throughout and the hardest reading.

Vocab

Study the classic SAT vocabulary list. Browse, flip flashcards, or quiz yourself.

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