Question

A箱中装有6张除颜色外完全相同的卡片，B箱中装有5张除颜色外完全相同的卡片.现用0，1，2三个数字给卡片标号，标号结果如下表所示：

从A箱中任取两张卡片，从B箱中任取1张卡片，用ξ表示取出的3张卡片上标号的积.

（1）求P（ξ=0）的值；

（2）求ξ的数学期望.

Answer 1

解:(1)P(ξ=0)=1-.                                                                ?

=.                                                                                                                     ?

(2)∵P(ξ=2)==,                                                                                   ?

P(ξ=4)==,                                                                        ?

P(ξ=8)==,                                                                                              ?

∴Eξ===.