Due to the bad weather, cotton yield poer mu is very low this year.

由于天气不好，今年棉花的亩产量很低。

And each began cohabitating with humans at different times in our evolutionary history. For example, " Mus musculus domesticus."

在我们进化史的不同，种老鼠都开始了与人类共存的生活。比如, “家鼠。”

" mu" " k" times " Fn" and the " mu" " k"

" mu" " k" 乘以 " Fn" 并且 " mu" " k" 将 0.

And then the last term is minus mu times minus mu, which is plus mu squared.

然后最后一项减 mu 乘以减 mu，即加 mu 的平方。

We learned the population mean was that mu letter.

我们了解到，总体均值用希腊字母μ表示。

The force of friction is always mu K FN.

摩擦力始终为 mu K FN。

One mu equals roughly 0.067 hectares.

一亩约等于 0. 067 公顷。

And actually, we could have just left the mu squared there.

实际上，我们本可以将 mu 平方留在那里。

" Mus musculus domesticus" .It began raiding human pantries around 12,000 years ago.

“Mus musculus domesticus”。大约在 12,000 年前，它开始袭击人类的储藏室。

" Now me mus tuddy my lessin, " went on the funny little thing.

“现在我必须好好学习， ” 那个有趣的小东西继续说道。

So pi mu is what we're working on.

所以π我们正在研究的东西。

If this was a whole population of numbers, we've figured out that this was mu.

如果这一组完整的数值总体，我们已经确定这就总体均值μ。

So minus mu K so the force of friction--- I'll just put force of friction.

所以减去 mu K 所以摩擦力 --- 我只输入摩擦力。

Times mu squared times the sum from i equals 1 to n.

乘以 mu 的平方乘以 i 等于 1 到 n 的总和。

And let's see, minus 2 times mu-- sorry, that mu doesn't look good.

让我们看看，减去 2 乘以 mu-- 抱歉，mu 看起来不太好。

So this is the Greek letter mu, and we put this k here for kinetic, or we can kind of say moving friction.

k表示" 动" (kinetic)该系数等于摩擦力的大小。

This negative mu will become a positive mu.

这个负的μ将变为正的μ。

So the mu squared term just gets factorized out.

所以 mu 平方的项刚好被分解了。

So mu sub P2 with a bar over it.

因此，P2的样本比例的抽样分布的均值，记作带横线的mu sub P2。

So this is also, we just have to remember that mu is equal to p.

因此，我们只需记住，μ等于p。