Free AP Statistics help

Statistics you can grab with your hands

Step-by-step guides for the questions students actually search, calculators that show every step, and draggable interactives for the ideas that never click from a textbook.

Browse the guides Try the interactives

Built on the new 5-unit AP Statistics course (first exam May 2027). From the maker of EconLearn, which the Colorado Department of Education lists in its economics resource bank.

▲ mean 9.38| median 8.50SD 4.84drag any point

Drag the far-right point further out: the mean follows it, the median barely moves. That is resistance, the first big idea of Unit 1.

Answers, not lectures

All 36 guides

How to find a z-score and read a z-tableFind a z-score with z = (x - mu) / sigma, then read the z-table to get a percentile. Worked examples for raw-to-z, percentile-to-raw, and negative z.What Does a P-Value Mean? (Plain-English Guide)A p-value is the chance of a result at least as extreme as yours if the null hypothesis is true. See common misreadings and a worked example.Central limit theorem, explained simplyThe central limit theorem says that for large samples, the sampling distribution of the sample mean is approximately normal whatever the population shape.t-test vs z-test: when to use eachUse a z-test for proportions and a t-test for means, since sigma is unknown and estimated by s. Includes a comparison table and two worked examples.How to calculate standard deviation by handCalculate standard deviation by hand in five steps: find the mean, square each deviation, divide by n-1 (sample) or n (population), then take the root.Which statistical test should I use? A decision guideChoosing a statistical test: use your data type, number of samples, and pairing to pick one-proportion z, chi-square, t tests, or regression.

Calculators that show their work

All 16 calculators

Every tool pairs the number you need with the steps behind it and a worked example, so the homework answer comes with the understanding the test requires.

Z-score calculator: value to z to percentileA z-score calculator converts a raw value, mean, and SD into z = (x - mu) / sigma, then into a percentile. For 82, 70, 8 you get z = 1.5 and 93.32%.Confidence interval calculator (mean and proportion)Find a confidence interval for a mean or proportion. Enter your sample data to get the interval, margin of error, and z* or t* critical value.Standard deviation calculator (and variance)A standard deviation and variance calculator squares each deviation, then divides by n-1 (sample) or n (population). For 4, 7, 8, 10, 16, s ~= 4.47.P-value calculator (from z, t, or chi-square)Convert a z, t, or chi-square test statistic to a p-value: one- or two-tailed for z and t, right tail for chi-square, with worked examples.

The new AP Statistics course, unit by unit

Course overview

College Board redesigned AP Statistics into five units effective Fall 2026. StatsLearn is built on the new framework from day one, sourced from the official course and exam description.