I realized I made a slight error in the last video, when I talk about the population and the sample mean.
So I will rewrite the equations.
I realize I made a slight notational error, and it might have confused you a little bit.
So just to review a little bit, it never hurts.
The mean of a population-- once again, that's mu-- the mean of a population is equal to, you take the sum of each of the data points.
So you take the sum-- that's that big sigma is for-- of each of the data points.
So x sub i.
I had written x sub n, before.
And if you review that last video, you can see why might be a little confusing.
And you start with the first data point.
下载全新《每日英语听力》客户端,查看完整内容