91影视

The values are

The sample mean's sampling distribution mean is equal.

${渭}_x=渭=40.125$

The sample as the units of the population mean are the units of the mean of the sampling distribution of the sample mean, and so the mean is $40.125\mathrm{mm}$

The values are,

$$\begin{gathered} 渭=40.125 \\ 蟽=0.002 \\ n=4 \end{gathered}$$

Let use the following formula

${蟽}_{\stackrel{炉}{x}}=\frac{蟽}{\sqrt{n}}$

The sample mean is the mean of the sampling distribution.

${渭}_{\stackrel{炉}{x}}=渭=40.125$

The standard deviation of the sample mean's sampling distribution is

${蟽}_x=\frac{蟽}{\sqrt{n}}=\frac{0.002}{\sqrt{4}}=\frac{0.002}{2}=0.001$

The units of the sampling distribution's standard deviation of the sample mean are the same as the units of the population standard deviation, so the standard deviation is $0.001\mathrm{mm}$.

In an hour, the sample mean diameter of four randomly selected axles fluctuates by an average of $0.001\mathrm{mm}$from the mean diameter of $40.125$