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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
(1)求两轮比赛结束乙得分为1分的概率;
(2)求不进行加赛甲就获得跳绳王的概率.
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A.![]() | B.![]() |
C.![]() | D.![]() |
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(1)列举数对
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba7204f43679af6935e494c59d40c6ff.png)
(2)记事件A为“二次函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed6d804ef44bfc64f824b0ccef71765e.png)
(3)记事件B为“关于x的一元二次方程
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e17e5145a2171ddaf4f4339f038ff152.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
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A.![]() | B.![]() | C.事件![]() ![]() | D.![]() |
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A.![]() | B.![]() | C.![]() | D.![]() |
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A.E与G是互斥事件; | B.F与I是互斥事件,且是对立事件; |
C.F与G是互斥事件; | D.G与I是互斥事件. |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
A.该同学仅随机选一个选项,能得分的概率是![]() |
B.该同学随机至少选择二个选项,能得分的概率是![]() |
C.该同学仅随机选三个选项,能得分的概率是![]() |
D.该同学随机选择选项,能得分的概率是![]() |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf31876698721a199c7c53c6b320aa86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b2a698891d42c70b597f0da4f215f09.png)
(1)求甲两轮至少猜对一个数学名词的概率;
(2)求“九章队”在两轮比赛中猜对三个数学名词的概率.
10 . 某物流公司专营从甲地到乙地的货运业务(货物全部用统一规格的包装箱包装),现统计了最近100天内每天可配送的货物量,按照可配送货物量(单位:箱)分成了以下几组:
,
,
,
,
,
,并绘制了如图所示的频率分布直方图(同一组数据用该组数据的区间中点值作代表,将频率视为概率).
(1)该物流公司负责人决定用分层抽样的方法从前3组中随机抽出11天的数据来分析可配送货物量少的原因,并从这11天的数据中再抽出3天的数据进行财务分析,求这3天的数据中至少有2天的数据来自
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/627a86a6ccc6968f95c9e26db5c4b80d.png)
(2)由频率分布直方图可以认为,该物流公司每日的可配送货物量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b68df477b3ee45ac0f725db00d465a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4de5dccfcaf5a40e069b12a9fed88059.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1100379a4385b9ce064847bc21760adc.png)
①试利用该正态分布,估计该物流公司2000天内货物配送量在区间内的天数(结果保留整数).
②该物流公司负责人根据每日的可配送货物量为公司装卸货物的员工制定了两种不同的工作奖励方案.
方案一:利用该频率分布直方图获取相关概率,采用直接发放奖金的方式奖励员工,按每日的可配送货物量划分为三级:时,奖励50元;
时,奖励80元;
时,奖励120元.
方案二:利用正态分布获取相关概率,采用抽奖的方式奖励员工,其中每日的可配送货物量不低于时有两次抽奖机会,每日的可配送货物量低于
时只有一次抽奖机会,每次抽奖的奖金及对应的概率分别为:
奖金 | 50 | 100 |
概率 |
小张为该公司装卸货物的一名员工,试从员工所得奖金的数学期望角度分析,小张选择哪种奖励方案对他更有利?附:若,则
,
.