試題詳解

288. For a pregnant woman, a certain test will give the outcome “not pregnant” with probability 0.10. For a non-pregnant woman, the test will give the outcome “pregnant” with probability 0.20. Of women who take the test, 20% are pregnant.

Calculate the probability that a woman is pregnant, given her test outcome is “pregnant.”
(A) 0.10
(B) 0.20
(C) 0.50
(D) 0.53
(E) 0.90