Mathematics for IGCSE & O level - Probability (Section 3 - No. 12)
If the probability of an event is 1/3, and it is repeated twice, what is the probability that the event happens exactly once?
1/9
2/9
4/9
1
คำอธิบาย
(1/3 * 2/3) + (2/3 * 1/3) = 2/9 + 2/9 = 4/9