中等MATH-PROB-009
P(A) = 0.6, P(B) = 0.5 and P(A ∩ B) = 0.2. What is P(A | B)?
A. 0.2
B. 0.6
C. 0.4✓ 答案
D. 0.3
解說
P(A | B) = P(A ∩ B) / P(B) = 0.2 / 0.5 = 0.4. The value 0.2 is the joint probability, and 0.6 is P(A), which ignores the condition.
P(A | B) = P(A ∩ B) / P(B) = 0.2 / 0.5 = 0.4. The value 0.2 is the joint probability, and 0.6 is P(A), which ignores the condition.