题目内容
设不等式组
表示的区域为A,不等式组
表示的区域为B,在区域A中任意取一点P
.
(Ⅰ)求点P落在区域B中的概率;
(Ⅱ)若
分别表示甲、乙两人各掷一次正方体骰子所得的点数,求点P落在区域B中的概率.
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
(Ⅰ)求点P落在区域B中的概率;
(Ⅱ)若

(1)
;(2)

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(Ⅰ)设区域A中任意一点P
为事件M.
因为区域A的面积为
,区域B在区域A的面积为
,
故
.
(Ⅱ)设点P
在集合B为事件N,
甲、乙两人各掷一次骰子所得的点P
的个数为36个,其中在区域B中的点P
有21个.
故


因为区域A的面积为


故

(Ⅱ)设点P

甲、乙两人各掷一次骰子所得的点P


故

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