Twelve different video games showing substance use were observed and the duration of times of game play $($in seconds$)$ are listed below. The design of the study justifies the assumption that the

sample can be treated as a simple random sample. Use the sample data to construct a $99\%$ confidence interval estimate of $,$ the standard deviation of the duration times of game play. Assume

that this sample was obtained from a population with a normal distribution.

Click the icon to view the table of Chi$-$Square critical values.

The confidence interval estimate is sec$.$

$($Round to one decimal place as needed.$)$