Twelve different video games showing substance use were observed and the duration of times of gameplay (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 gameplay. Assume that this sample was obtained from a population with a normal distribution.

3876,3905,5042,5006,4725,4550,4240,4446,4894,4431,4135,3910

The confidence interval estimate is

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