Probability Formula

• P(A) = n(A)/n(S)

P(A) is the probability of an event “A” n(A) is the number of favourable outcomes n(S) is the total number of events in the sample space

• Probability Range =0 ≤ P(A) ≤ 1
• Rule of Addition= P(A∪B) = P(A) + P(B) – P(A∩B)
• Rule of Complementary Events= P(A’) + P(A) = 1
• Disjoint Events= P(A∩B) = 0
• Independent Events= P(A∩B) = P(A) ⋅ P(B)
• Conditional Probability =P(A | B) = P(A∩B) / P(B)
• Bayes Formula =P(A | B) = P(B | A) ⋅ P(A) / P(B)

Formula for Conditional Probability

• Conditional Probability of A given B P (A|B) = P(A ∩ B)⁄P(B)
• Conditional Probability of B given A P (B|A) = P(B ∩ A)⁄P(A)

Binomial Probability Formula

• P (X) = nCx p^x q^(n – x)

n = Total number of trials x = Total number of successful trials p = probability of success in a single trial q = probability of failure in a single trial = 1-p