Statistics & probability

Mean

x̄ = Σx / n

Median (odd n)

((n + 1)/2)th value

Empirical relation

Mode = 3 Median − 2 Mean

Probability

P(E) = favourable / total outcomes

0 ≤ P(E) ≤ 1

Complement

P(not E) = 1 − P(E)

Permutation & combination

ⁿPᵣ = n!/(n − r)!, ⁿCᵣ = n!/[r!(n − r)!]

Mean of grouped data

x̄ = Σfx / Σf

Variance

σ² = Σx²/n − (Σx/n)²

Standard deviation σ = √variance