試題詳解

318. Data on a certain pregnancy test show that a pregnant woman will test negative or not pregnant 10% of the time, while a non-pregnant woman will test positive 20% of the time.

Thirty percent of the women who take the test are pregnant.

Calculate the probability that a woman is pregnant given that her test outcome is positive.
(A) 0.18
(B) 0.30
(C) 0.66
(D) 0.82
(E) 0.90