Probability Tutor Help
Apply the addition and multiplication rules, tell independent from dependent events, and count with permutations and combinations.
1 Concept recap
The essentials of Probability Rules & Counting, on one screen.
1 Concept recap
Basic
P = favorable / total, always between 0 and 1.
Or / and
P(A or B) = P(A) + P(B) − P(A and B). Independent: P(A and B) = P(A)×P(B). Without replacement: recompute given the first draw.
Counting
Order matters → P(n,k) = n!/(n−k)!. Order does not → C(n,k) = n!/(k!(n−k)!).
Complement
P(at least one) = 1 − P(none).
2 Ask a tutor
Demo form: this form is a design preview only. It does not send your message anywhere — no backend is connected and nothing is stored.