1 . 有三种不同的果树苗
,
,
,经引种试验后发现,引种树苗
的自然成活率为0.6,引种树苗
,
的自然成活率均为
.
(1)任取树苗
,
,
各一株,设自然成活的株数为
,求
的分布列及
;
(2)将(1)中
的取得最小值时的
的值作为
种树苗自然成活的概率.该农户决定引种
株
种树苗,引种后没有自然成活的树苗中有80%的树苗可经过人工栽培技术处理,处理后成活的概率为0.5,其余的树苗不能成活.
①求一株
种树苗最终成活的概率;
②若每株树苗引种最终成活后可获利400元,不成活的每株亏损60元,该农户为了获利不低于30万元,应至少引种
种树苗多少株?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56fba802c9a10f87a2e4597d1b273f76.png)
(1)任取树苗
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5bf3baba074e8aeb6f3ea117865bbd1b.png)
(2)将(1)中
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5bf3baba074e8aeb6f3ea117865bbd1b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1010846eeec6c9da29640f5aa3f8738.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef65559a6b44930addc23adeb8d854c9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
①求一株
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
②若每株树苗引种最终成活后可获利400元,不成活的每株亏损60元,该农户为了获利不低于30万元,应至少引种
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
您最近一年使用:0次
2023-06-18更新
|
231次组卷
|
2卷引用:广西壮族自治区北海市2023-2024学年高二上学期期末教学质量检测数学试题
2 . 有甲、乙两个班级进行数学考试,按照大于或等于90分为优秀,90分以下为非优秀统计成绩后得到如下2×2列联表,且从全部210人中随机抽取1人为非优秀的概率为
.
(1)请完成上面的2×2列联表,并判断能否有99%的把握认为“成绩与班级有关”;
(2)从全部210人中有放回地随机抽取3次,每次抽取1人,记被抽取的3人中的优秀人数为
,若每次抽取的结果是相互独立的,求
的分布列及数学期望
.
注:
,
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ab44a7dc9c035687a33f6e065392359.png)
优秀 | 非优秀 | 总计 | |
甲班 | 90 | ||
乙班 | 40 | ||
总计 | 20 |
(2)从全部210人中有放回地随机抽取3次,每次抽取1人,记被抽取的3人中的优秀人数为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b734e8f1546481e3eb4976008a045de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b734e8f1546481e3eb4976008a045de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a18cb978c023350805e1dfc581988b5.png)
注:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/353f9ac2632b47de33964839b460e77c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/356b05e46b10ee51c3e43546d73ec96c.png)
0.05 | 0.01 | |
3.841 | 6.635 |
您最近一年使用:0次
3 . 设在一次试验中事件A出现的概率为p,在n次独立重复试验中事件A出现k次的概率为
,则( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dbe0f61ec213734b7ae080719fa5cdd3.png)
A.![]() | B.![]() |
C.![]() | D.![]() |
您最近一年使用:0次
2018-03-01更新
|
340次组卷
|
2卷引用:广西北海市2022-2023学年高二下学期期中数学试题