Further Probability (A Level only) (Edexcel A-Level Mathematics): Flashcards

$P(A) = \frac{\text{Number of favorable outcomes}}{\text{Total outcomes}}$

$P(A') = 1 - P(A)$

$P(A \cup B) = P(A) + P(B) - P(A \cap B)$

$P(A \cap B) = P(A) \times P(B)$

$P(A | B) = P(A \cap B) / P(B)$

$P(A) = \Sigma P(B_i) \times P(A | B_i)$ for exhaustive events

$P(B_i | A) = P(B_i) \times P(A | B_i) / P(A)$

$P(\text{at least one}) = 1 - P(\text{none})$

$P(\text{Rolling a 4}) = \frac{1}{6}$

$P(A \cap B) = P(A) \times P(B | A)$