alleryGiven P(A or B) = 0.8, P(A) = 0.5 and P(A and B) = 0.2, the value of P(B) is:
A0.30 exactly
B0.10 exactly
C0.50 exactly
D0.60 exactly
Answer & Solution
Correct answer: C. 0.50 exactly
1. Rearrange the addition rule: P(B) = P(A or B) - P(A) + P(A and B).
2. Substitute: 0.8 - 0.5 + 0.2.
3. P(B) = 0.5.
_Source: syllabus Mathematics, Ch 14 'Probability' (kemh114)_
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