Don’t memorise distributions as a flat chart. Memorise the QUESTION each one answers, and the right family pops out automatically. The relationships form a small chain: Bernoulli is the atom, Binomial sums it, Poisson is its rare-event limit, Exponential is the wait between Poisson events, Gamma is the sum of those waits, Normal is the limit of finite-variance sums (CLT), Lognormal is its multiplicative cousin.
This page is intentionally light — one decision-tree step that links to the full tutorial for each distribution. Practice on this page is just one meta-question (name the distribution given a story). The real practice for each lives in its own tutorial.
✓ Intro · expand
Try first (productive failure)
Before the worked example: spend 60 seconds taking your best shot at this.
A guess is fine — being briefly wrong about a problem makes the explanation
land harder when you read it. This appears once per tutorial; skip
if you already know the trick.
60s
✓ Try first · expand
Worked example
This page is a connector. Pick the distribution that fits your question; the linked tutorial has the full derivation, worked example, and practice.
✓ Worked example · expand
Practice 1 of 3Type a fraction, decimal, or expression — mathjs parses it.
✓ Practice · expand
Reflection
In your own words, what’s the difference between “number of events in a window” and “time until the next event”? Which distribution belongs to each?
