某班学生《卫生统计学》考试成绩表如下：
成绩(分)
频率(%)()/
50—60
6.7
60—70
13.3
70—80
30.0
80—90
36.7
90—100
13.3
合计
100.0
试计算该班学生的平均成绩。/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif
成绩(分)
频率(%)()/
50—60
6.7
60—70
13.3
70—80
30.0
80—90
36.7
90—100
13.3
合计
100.0
试计算该班学生的平均成绩。/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif
举一反三
- 已知：则反应的稳定常数为/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif
- 3.The swimmer to cross the English Channel but failed./js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif
- 在力法方程中，称为 ，表示 ，称为 ，表示 。/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif
- 6．合理的刀具耐用度包括 与 两种。/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif
- 所谓交流负反馈是指 的反馈。 （A．放大倍数为负数， B．变小，C．变大。）/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif/js/editor20150812/themes/default/images/spacer.gif