题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000916-56563.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000916-36234.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000916-36975.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000917-65230.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000918-91256.png)
(1)定义横、纵坐标为整数的点为“整点”. 在区域
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000916-36975.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000918-91256.png)
(2)在区域
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000916-36975.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000918-91256.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000918-21486.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000918-21486.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000918-87543.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000918-21486.png)
![]() | 0 | 1 | 2 | 3 |
![]() | ![]() | ![]() | ![]() | ![]() |
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000918-21486.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000920-73315.png)
解析
试题分析:(1)依题可知平面区域
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000916-36975.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000920-98837.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000918-91256.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000920-74214.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000920-20474.png)
(2)依题可得,平面区域
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000916-36975.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000921-52969.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000921-46578.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000921-87278.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000922-37734.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000918-91256.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000916-36975.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000922-29671.png)
在区域
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000916-36975.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000918-91256.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000922-89889.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000918-21486.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000922-48663.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000922-21331.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000923-73736.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000923-92470.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000923-25894.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000918-21486.png)
![]() | 0 | 1 | 2 | 3 |
![]() | ![]() | ![]() | ![]() | ![]() |
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000918-21486.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000920-73315.png)
点评:古典概型概率的求解先要找到所有基本事件总数及满足题意要求的基本事件种数,然后求其比值;分布列的题目要根据题目所描述的问题找到随机变量可取的值,再依次求出各值对应的概率列表即可
核心考点
试题【在平面内,不等式确定的平面区域为,不等式组确定的平面区域为.(1)定义横、纵坐标为整数的点为“整点”. 在区域中任取3个“整点”,求这些“整点”中恰好有2个“整】;主要考察你对离散型随机变量均值与方差等知识点的理解。[详细]
举一反三
付款方式 | 分1期 | 分2期 | 分3期 | 分4期 | 分5期 |
频数 | 40 | 20 | ![]() | 10 | ![]() |
(Ⅰ)求上表中
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000901-91494.png)
(Ⅱ)若以频率作为概率,求事件
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000902-11862.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000902-71927.png)
(Ⅲ)求Y的分布列及数学期望EY.
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000855-68198.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000855-68198.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000855-68198.png)
| 科目甲 | 科目乙 | 总计 |
第一小组 | 1 | 5 | 6 |
第二小组 | 2 | 4 | 6 |
总计 | 3 | 9 | 12 |
(1)求选出的4 人均选科目乙的概率;
(2)设
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000839-80701.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000839-80701.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000832-95159.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000832-95159.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000832-13930.png)
(Ⅰ)求决赛中甲、乙两支队伍恰好排在前两位的概率;
(Ⅱ)若决赛中甲队和乙队之间间隔的队伍数记为
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000825-51384.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030000825-51384.png)
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