Probability Simulator — coin, dice, roulette (theory vs empirical)

Fix the RNG seed, run coin, weighted dice, and roulette experiments, and watch theory vs empirical tallies, Wilson intervals, convergence bands, and How it's calculated steps update in real time.

Ideal for probability lessons: deterministic seeds keep classrooms in sync, CSV and LaTeX exports let you document outcomes, and the staged explanations reinforce how probabilities, expectations, and confidence intervals connect.

Other languages: ja | en | es | zh-CN

Choose among coin flips with custom p(Heads), weighted six-sided dice, or European/American roulette bets. The simulator compares theory and empirical ratios, shows Wilson 95% confidence intervals for binary outcomes, tracks running convergence, and records the exact steps it takes so you can explain them back to the class.

Need extra documentation? Use the CSV export for raw counts, the LaTeX summary for worksheets, and the shareable URL to resume the exact scenario in your next session.

Controls

General settings
Coin settings

Progress: 0% (0/0)

Result

How it's calculated

    Distribution (theory vs empirical)

    Blue bars track empirical frequencies while the lighter overlay shows theoretical probabilities. Differences are labeled above each category for quick reference.

    Running estimate vs trials

    The solid line shows the running proportion. The dashed line marks the theoretical value and the shaded band gives the 95% confidence interval as trials accumulate.

    Teaching tips

    FAQ

    How can I verify the RNG sequence in class?

    Pick the published acceptance cases—e.g., seed 12345, 100 coin flips—then show how the simulator reports 44 heads every time. Switching devices yields the same outcome because the RNG and seed are fixed.

    Can I export the run to share with students?

    Yes. Use CSV for raw counts and running estimates, copy the LaTeX summary for worksheets, and share the auto-generated URL to reload the same experiment later.