RPA卡环组由近中<img src="https://nimg.ppkao.com/2016-01/chenyalin/2016010809115182583.jpg?sign=e901db5947bc4a660c94b12bf95dfe88&t=62e46dff" />支托、()和圆环形卡环固位臂组成。
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A、某班40名学生统计成绩分组资料如下,试计算全班的平均成绩。
<img src="https://img.ppkao.com/2018-07/tangxueping/2018072215153779974.jpg" />
A、A.<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309154866509.jpg" />低电平,<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309155838776.jpg" />三态,<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309155342124.jpg" />低电平
B.<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309154866509.jpg" />三态,<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309155838776.jpg" />低电平,<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309155342124.jpg" />高电平
C.<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309154866509.jpg" />低电平,<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309155838776.jpg" />高电平,<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309155342124.jpg" />高电平
D.<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309154866509.jpg" />高电平,<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309155838776.jpg" />低电平,<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309155342124.jpg" />高电平
A、A.<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120716370781231.jpg" />不变,<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120716372262539.jpg" />增大
B.<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120716370781231.jpg" />减小,<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120716372262539.jpg" />不变
C.<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120716370781231.jpg" />减小,<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120716372262539.jpg" />增大
D.<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120716370781231.jpg" />增大,<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120716372262539.jpg" />减小
A、A.<img src="https://img.ppkao.com/2018-04/zhouyun/20180412175605391.jpg" />
B.<img src="https://img.ppkao.com/2018-04/zhouyun/2018041217562114745.jpg" />
C.<img src="https://img.ppkao.com/2018-04/zhouyun/2018041217562651092.jpg" />
D.<img src="https://img.ppkao.com/2018-04/zhouyun/2018041217562929580.jpg" />
E.<img src="https://img.ppkao.com/2018-04/zhouyun/2018041217563332745.jpg" />
A、已知一组数据的协方差矩阵为<img src="https://img.ppkao.com/2018-10/zenglei/2018101816094725138.jpg" />,试问: