91Ó°ÊÓ

We are given sample of prices of mobile homes in manufactured housing statistics of U.S. Census Bureau.

According to empirical rule ,

For $95\%$of the sample there should be two standard deviations at either side of mean, therefore,

$$\begin{gathered} \overline{x}-2s=63.3-2\left(7.9\right)=47.5 \\ \overline{x}+2s=63.3+2\left(7.9\right)=79.1 \end{gathered}$$

Approximately $95\%$of the mobile homes in the sample have prices between $47.5$thousand and$79.1$ thousand.

We are given sample of prices of mobile homes in manufactured housing statistics of U.S. Census Bureau.

According to empirical rule,

$$\begin{gathered} \overline{x}-ks=39.6 \\ 63.3-k\left(7.9\right)=39.6 \\ k=3 \\ \overline{x}+ks=80.70 \\ 63.3+k\left(7.9\right)=87.0 \\ k=3 \end{gathered}$$

Now, as $k=3$that means $99.7\%$of mobiles in the sample lies in given range.

$250×\frac{99.7}{100}=249.25≈249$

$99.7\%$of the mobile homes in the sample have prices between $39.6$ thousand and $87.0$ thousand.

We are given sample of prices of mobile homes in manufactured housing statistics of U.S. Census Bureau.

According to empirical rule,

$$\begin{gathered} \overline{x}-ks=55.4 \\ 63.3-k\left(7.9\right)=55.4 \\ k=1 \\ \overline{x}+ks=71.2 \\ 63.3+k\left(7.9\right)=71.2 \\ k=1 \end{gathered}$$

Now, as that means $68\%$of mobiles in the sample lies in given range.

$250×\frac{68}{100}=170$

$170$of the mobile homes in the sample have prices between $55.4$thousand and $71.2$ thousand.