某市某年随机抽样调查21岁男大学生20人的脉搏数(次/分),其均数为76.1,标准差为9.32,该市21岁男大学生脉搏数的95%置信区间是。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/042b7dcd534a4270a09d1a9bdcefbfb6.png
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- 某市某年随机抽样调查21岁男大学生20人的脉搏数(次/分),其均数为76.1,标...a09d1a9bdcefbfb6.png
- 某地调查了60岁以上冠心病患者28名的血清胆固醇,其均数为230.8mg/dl,标准差为54.9mg/dl,60岁以上冠心病患者血清胆固醇95%的置信区间是。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/ea26b30a2e4548e998fe7d231e4d7c95.png
- 已知正常成年人脉搏均数为 70 次/分。现随机抽取某病成年病人36 人,测得脉搏均数为 72.12 次/分,标准差为 5.09 次/分。问能否认为该病病人脉搏均数与正常成年人脉搏均数不同?
- 某地调查了40~50岁冠心病患者500名的血清胆固醇,其均数为228.6mg/dl,标准差为46.8mg/dl,该年龄组冠心病患者血清胆固醇99%的置信区间是。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/41aa340aa136421a85c8b2ce0c326648.png
- 已知串联支路为<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/65b91bc067d14873a38d0c4675b53329.png"/> , ,则其传递函数为( ) A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/8bc361d7b437451dac5c0c42c3213311.png"/> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/7db9751653e24eba9f152b6937c8c256.png"/> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/a4b7ab7e122b40068ce6b78635486bae.png"/> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/a6b34e5a8a764d5c9b78c725d7b77ed4.png"/>