NO.PZ2023091601000009
问题如下：
In
country X, the probability that a letter sent through the postal system reaches
its destination is 2/3. Assume that each postal delivery is independent of
every other postal delivery, and assume that if a wife receives a letter from
her husband, she will certainly mail a response to her husband. Suppose a man
in country X mails a letter to his wife (also in country X) through the postal
system. If the man does not receive a response letter from his wife, what is
the probability that his wife received his letter?
选项：
A.1/3
B.3/5
C.2/3
D.2/5
解释：
(Notices: if the
wife did not receive the letter, she would not sent response to the man.)
Note:
A: the wife
received the letter;
B: the man received a response letter from his
wife;
The question “If the man does not receive a
response letter from his wife, what is the probability that his wife received
his letter?” is equal to figure out P(A|
).
这个不应该是妻子收到信的前提下，丈夫未收到信吗？也就是（2/3）*（1/3）=2/9？
