A sample of 3 measurements are taken and recorded: [tex]x=8[/tex], [tex]y=10[/tex], and [tex]z=5[/tex]. The sample mean is: [tex]\bar{x}=\frac{x+y+z}{3}=7.67[/tex].

Fill in the table below.
\begin{tabular}{|l|l|}
\hline
[tex]$a_i$[/tex] & [tex]$\left(a_i-\bar{x}\right)^2$[/tex] \\
\hline
[tex]$x$[/tex] & Ex: [tex]$5.34$[/tex] \\
\hline
[tex]$y$[/tex] & Ex: [tex]$5.34$[/tex] \\
\hline
[tex]$z$[/tex] & Ex: [tex]$5.34$[/tex] \\
\hline
\end{tabular}

[tex]\[
s^2=\frac{(x-\bar{x})^2+(y-\bar{x})^2+(z-\bar{x})^2}{2}=\text { EX: } 5.34 \\
s=\sqrt{\frac{(x-\bar{x})^2+(y-\bar{x})^2+(z-\bar{x})^2}{2}}=\text { EX: } 5.34
\][/tex]



Answer :

Let's go through the calculations step-by-step.

1. Given Data:
- Measurements: [tex]\( x = 8 \)[/tex], [tex]\( y = 10 \)[/tex], [tex]\( z = 5 \)[/tex]
- Sample Mean ([tex]\( \bar{x} \)[/tex]): [tex]\( \bar{x} = \frac{x + y + z}{3} = 7.67 \)[/tex]

2. Calculate the squared differences from the mean for each measurement:

- For [tex]\( x \)[/tex]:
[tex]\[ (x - \bar{x})^2 = (8 - 7.67)^2 = 0.1089 \][/tex]

- For [tex]\( y \)[/tex]:
[tex]\[ (y - \bar{x})^2 = (10 - 7.67)^2 = 5.4289 \][/tex]

- For [tex]\( z \)[/tex]:
[tex]\[ (z - \bar{x})^2 = (5 - 7.67)^2 = 7.1289 \][/tex]

3. Fill in the table with these values:
[tex]\[ \begin{array}{|c|c|} \hline a_i & (a_i - \bar{x})^2 \\ \hline x & 0.1089 \\ \hline y & 5.4289 \\ \hline z & 7.1289 \\ \hline \end{array} \][/tex]

4. Calculate the sample variance ([tex]\( s^2 \)[/tex]):
[tex]\[ s^2 = \frac{(x - \bar{x})^2 + (y - \bar{x})^2 + (z - \bar{x})^2}{2} \][/tex]
Substitute the values:
[tex]\[ s^2 = \frac{0.1089 + 5.4289 + 7.1289}{2} = \frac{12.6667}{2} = 6.33335 \][/tex]

5. Calculate the sample standard deviation ([tex]\( s \)[/tex]):
[tex]\[ s = \sqrt{s^2} = \sqrt{6.33335} = 2.5166 \][/tex]

Finally, present the calculated values:

[tex]\[ \begin{array}{|c|c|} \hline a_i & (a_i - \bar{x})^2 \\ \hline x & 0.1089 \\ \hline y & 5.4289 \\ \hline z & 7.1289 \\ \hline \end{array} \][/tex]

[tex]\[ s^2 = \frac{(x - \bar{x})^2 + (y - \bar{x})^2 + (z - \bar{x})^2}{2} = 6.33335 \][/tex]

[tex]\[ s = \sqrt{s^2} = 2.5166 \][/tex]