奇怪,一道英文的数学方差问题,怎么不对啊!
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奇怪,一道英文的数学方差问题,怎么不对啊!
The ages of students in a class have been put into the frequency
distribution below.
Age Number of Students
18 3
19 5
20 28
21 4
What is the standard deviation for this
(population) set of data?
选项是:
a.1.12
b.0.703
c.1.35
d.1.25
e.0.494
平均数是19.然后我得到1.5^2x7+0.25x33 的和除以40,得到0.再加根号!
The ages of students in a class have been put into the frequency
distribution below.
Age Number of Students
18 3
19 5
20 28
21 4
What is the standard deviation for this
(population) set of data?
选项是:
a.1.12
b.0.703
c.1.35
d.1.25
e.0.494
平均数是19.然后我得到1.5^2x7+0.25x33 的和除以40,得到0.再加根号!
![奇怪,一道英文的数学方差问题,怎么不对啊!](/uploads/image/z/18984944-56-4.jpg?t=%E5%A5%87%E6%80%AA%2C%E4%B8%80%E9%81%93%E8%8B%B1%E6%96%87%E7%9A%84%E6%95%B0%E5%AD%A6%E6%96%B9%E5%B7%AE%E9%97%AE%E9%A2%98%2C%E6%80%8E%E4%B9%88%E4%B8%8D%E5%AF%B9%E5%95%8A%21)
平均数是19.825 ,方差0.703,选