中等MATH-PROB-002
P(A) = 0.4, P(B) = 0.5 and P(A ∩ B) = 0.2. What is P(A ∪ B)?
A. 0.9
B. 0.2
C. 0.7✓ 答案
D. 1.1
解說
P(A ∪ B) = 0.4 + 0.5 − 0.2 = 0.7. The value 0.9 forgets to subtract the intersection. A probability cannot be 1.1.
P(A ∪ B) = 0.4 + 0.5 − 0.2 = 0.7. The value 0.9 forgets to subtract the intersection. A probability cannot be 1.1.