E
E
E：抓到娃娃
H
H
H：坐地铁
H
ˉ
\bar H
Hˉ：坐公交
P
(
E
)
=
P
(
H
)
P
(
E
∣
H
)
+
P
(
H
‾
)
P
(
E
∣
H
‾
)
P({E}) = P({H}) P({E} \mid {H}) + {P}(\overline{{H}}) {P}({E} \mid \overline{{H}})
P(E)=P(H)P(E∣H)+P(H)P(E∣H)
P
(
H
∣
E
)
=
P
(
E
∣
H
)
P
(
H
)
P
(
E
)
=
0.6
P({H} \mid {E}) = \dfrac{{P}({E} \mid {H}) {P}({H})}{{P}({E})} = 0.6
P(H∣E)=P(E)P(E∣H)P(H)=0.6
P
(
H
‾
∣
E
)
=
P
(
E
∣
H
‾
)
P
(
H
‾
)
P
(
E
)
=
0.4
P(\overline{{H}} \mid {E}) = \dfrac{{P}({E} \mid \overline{{H}}) {P}(\overline{{H}})}{{P}({E})} = 0.4
P(H∣E)=P(E)P(E∣H)P(H)=0.4
面积为1的概率空间，任何事件都对应概率空间的一个子集，事件发生的概率是子集的面积。
