Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

binomial distribution

The count of successes across n independent Bernoulli trials, each with the same success probability.

$X\sim\operatorname{Binomial}(n,p)$ : $p(k)=\binom{n}{k}p^k(1-p)^{n-k}$ .