NO.PZ2020011901000031
问题如下：
Using Table 2.1, what is the probability that a woman aged 70 will live to age 90:
选项：
A.0.29650
0.35801
0.31166
It is impossible to tell from the information in the table.
解释：
B.
It is
(Probability of Survival from Birth Until Age 90)/(Probability of Survival from Birth Until Age 70)
=0.29650/0.82818
= 0.35801
”我们假设
A=活到70岁
B=活到90岁
P(A)=0.82818 活到70岁的概率
P(B)=0.2965 活到90岁的概率
要求的是70~90的概率 P(B|A)=在活到70岁的情况下活到了90岁 也就是70~90岁的概率=P(AB)/P(A)
此时已知P(A)
P(AB)是两个事件的交集，就是即活到了70岁又活到了90岁的概率，那其实就是P(B)=0.2965“
老师的这个解答有些疑问，这个0.2965到底是P(B)还是P(AB)? 为什么？
