# Given two events A and B if the probability that A occurs is 0.3, the probability that B occurs is 0.4 and the probability that A or B?

Occurs is .55 what is P(A/B)

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- PuzzlingLv 79 months agoFavourite answer
The probability of either A or B is:P(A or B) = P(A) + P(B) - P(A and B)

We can rewrite that in terms of P(A and B):

P(A and B) = P(A) + P(B) - P(A or B)

Plug in your values:P(A and B) = 0.3 + 0.4 - 0.55

P(A and B) = 0.7 - 0.55

P(A and B) = 0.15

The conditional probability formula is:

P(A | B) = P(A and B) / P(B)

Plug in your values:P(A | B) = 0.15 / 0.4

= 15/40

= 3/8

Answer:

P(A | B) = 3/8 (or 0.375)

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