Reach your peak.
A quick run every day, an explanation for every question, and full-length tests on official timing.
Full-length tests
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.
How it works
A quick run with three hearts. String right answers together and the questions get harder and the points multiply.
Every question is tagged by domain and skill, and every answer comes with an explanation.
Practice any single skill at any difficulty, or just the questions you got wrong.
Come back tomorrow and climb. Progress shows your accuracy and your strongest skills.
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.
9 easy, 9 medium, 9 hard and 9 challenging questions free every day, each with a full explanation. Filter by section, domain, skill and difficulty. Resets at midnight Central Time.
Take any test on official timing, extended 1.5× time, or untimed to focus purely on accuracy.
Four modules in official order. The second module of each section adapts to how you did on the first.
1,023 essential SAT words. Browse the list, flip flashcards, or quiz yourself.
Accuracy across daily practice and full tests, your strongest skills, and the ones that need the most help.
PEAK Survivor, Hole and Peak Defense: three games powered by SAT practice questions.
Explanations
Not just the right letter: how to get there, and why the tempting answer is wrong.
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?
Check with $100: $100→then$120→then$96
Up 20% means × 1.20. Down 20% means × 0.80.
1.20 × 0.80 = 0.96
The final price is 96% of the original. That’s B.
The 20% cut is taken from the higher price, so it removes more than the 20% increase added.
Test day
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.
27 questions32 min
27 questions32 min
10 min
22 questions35 min
22 questions35 min
98 questions · 2 hr 14 min of testing, plus the break
Plans
The free plan is the real thing, not a trial. Pro removes the limits. Peak adds the full course and a plan to test day.
$0no card needed
$20a month, or $200 a year
$29a month, or $280 a year
Prices in US dollars. Cancel anytime.
FAQ
The Daily, plus 36 practice questions every day: 9 easy, 9 medium, 9 hard and 9 challenging, each with a full explanation. Full-length Test A, Challenge Test 1 and all 1,023 vocabulary words are free too, as are the 20-question diagnostic, each Learn module’s overview and first lesson, and PEAK Survivor’s first map. 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, and every game map and level. 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 Central Time. You get a fresh 9 easy, 9 medium, 9 hard and 9 challenging.
No. Peakscor is an independent SAT practice tool, not affiliated with the College Board. Scores shown are estimates.
Free, no card.
Inference and margin of error · Lesson 3
Imagine estimating the percent of a city's adults who own a bike. A random sample of 40 adults could, by luck, include more bike owners than usual. With 1,000 adults, lucky streaks like that tend to even out, so the estimate tends to land closer to the true value.
That is why, for the same population, the same question and the same confidence level, a larger random sample usually gives a smaller margin of error. A smaller margin means a narrower interval, so the estimate is more precise.
Two limits to keep straight. First, a larger sample shrinks the margin of error but never removes it: any sample smaller than the whole population leaves some uncertainty. Second, the margin of error only covers the luck of random selection. If the sample is biased, for example people who chose to answer an online poll, a bigger sample repeats the same bias.
Spread matters too. For a mean, when the values in the population are more spread out, the margin of error tends to be larger for the same sample size. The items in this lesson compare sample sizes.
You don't need a formula. Same population, same question, same confidence level: bigger random sample, smaller margin of error.
Which of the following is most likely true about the margins of error?
Which of the following plans is most likely to give a smaller margin of error while still allowing the results to be generalized to all the city's adult residents?
The margin of error is 0 or the estimate is guaranteed to equal the true value is never supported for a sample. A bigger random sample makes the margin smaller, not zero.
A choice may offer a much larger sample chosen in a biased way, such as volunteers or people in one place. The margin of error describes the luck of random selection only, so a bigger biased sample is not a better one.
A larger margin of error goes with a smaller sample. If two random surveys of the same population ask the same question at the same confidence level, the one with the wider interval most likely had fewer people.
Desmos isn't faster here, and there is nothing to compute. These questions test one idea: for the same population, question and confidence level, a larger random sample usually means a smaller margin of error.
Answer by comparing sample sizes and checking that each sample is random. Typing numbers into Desmos won't tell you whether a sample is biased.
Choose a section, then practice a whole domain or drill a single skill.
Each test mirrors the digital SAT: 98 questions across four modules, 2 hr 14 min on official timing.
Same 98-question format, but every question is drawn from the toughest SAT material: Challenging-tier math throughout and the hardest reading.
Study the classic SAT vocabulary list. Browse, flip flashcards, or quiz yourself.
Practice free every day. Pro removes the limits. Peak adds the full course and a plan to test day.
Prices in USD. Switch or cancel your plan at any time.
Online payment hasn’t launched, so nothing here asks for a card. Everything on the free plan stays free.
Save your progress and pick up where you left off.
Your account keeps game coins, characters and map progress in sync across devices. Practice history stays on this device.