Conditional probability

M=Math test was .73F= French test was .65

Neither M or F = .08

1st find Combined Probability

• M=Math test was .73• F= French test

was .65• Neither M or F = .08• Combined formula• P(M ∩ F) = P(M) + P(F) – P (MUF)

• .46 = .73 + .65 - .92• Next is conditional

.27 .19.46.08

M

NF

Conditional probability

• Two steps – find combined probability

• P(M ∩ F) = P(M) + P(F) – P (MUF)• .46 = .73 + .65 - .92

– Calculate conditional Probability• P(A | B) = Combined/P(second event)• .46/.65 = .708 passed both