A sample of eight repair records for a certain fiber-optic

Step 1 of 2

Here we have to find 95% confidence interval

Now we have to find mean and standard deviation

\(\begin{array}{|l|l|} \hline x & (x-\bar{x})^{2} \\ \hline 30 & 27.5625 \\ \hline 35 & 105.0625 \\ \hline 19 & 33.0625 \\ \hline 23 & 3.0625 \\ \hline 27 & 5.0625 \\ \hline 22 & 7.5625 \\ \hline 26 & 1.5625 \\ \hline 16 & 76.5625 \\ \hline \text { Total=198 } & \text { Total=259.5 } \\ \hline \end{array}\)

\(\text { Mean } \begin{aligned} \bar{X} & =\Sigma X / n \\ & =198 / 8 \\ & =24.75 \end{aligned}\)

\(\begin{array}{l}\text{Standard deviation } (\mathrm{s})=\sqrt{\frac{\Sigma(x-\bar{x})^{2}}{n-1}}\\ =\sqrt{\frac{259.5}{8-1}} \\ =6.09\end{array}\)