정규분포
Normal distribution — bell of stillness
f(x) = (1/σ√2π) · e-(x-μ)²/2σ²
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A herbarium of probability — pressed concepts, hand-bound, slightly faded.
Garden of concepts — six pressed leaves, six theorems
Normal distribution — bell of stillness
f(x) = (1/σ√2π) · e-(x-μ)²/2σ²
Binomial — repeated coins, counted
P(k) = (n,k) pk (1-p)n-k
Bernoulli — a single coin in dim light
P(X=1) = p, P(X=0) = 1-p
Poisson — rare arrivals, gentle clatter
P(k) = (λke-λ) / k!
Conditional — what if, what given
P(A|B) = P(A∩B) / P(B)
Bayes — what we know, updated
P(H|E) = P(E|H)P(H) / P(E)
Branching paths — chance unfolds, root to tip
Two consecutive days of weather, drawn as ink on rice paper. The thicker the branch, the more often this path is taken.
Field-journal of common distributions
{0, 1}pp(1-p){0, 1, …, n}npnp(1-p){0, 1, 2, …}λλ[a, b](a+b)/2(b-a)²/12(-∞, ∞)μσ²[0, ∞)1/λ1/λ²— annotated by an unhurried hand, in fading ink —