試題詳解

147. In a certain group of cancer patients, each patient's cancer is classified in exactly one of the following five stages: stage 0, stage 1, stage 2, stage 3, or stage 4.
i) 75% of the patients in the group have stage 2 or lower.
ii) 80% of the patients in the group have stage 1 or higher.
iii) 80% of the patients in the group have stage 0, 1, 3, or 4.
One patient from the group is randomly selected.

Calculate the probability that the selected patient's cancer is stage 1.
(A) 0.20
(B) 0.25
(C) 0.35
(D) 0.48
(E) 0.65