某市250名8岁男孩体重有95%的人在18～30kg范围内，由此可推知此250名男孩体重的标准差大约为

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku_ where sourceid='18122' and id < 1535871 and id<>'1535871' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='18122' and id > 1535871 and id<>'1535871' order by id asc limit 5