Question

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

an

80%

confidence interval estimate of sigmaσ​, the standard deviation of the duration times of game play. Assume that this sample was obtained from a population with a normal distribution.

3835	4680	4451	4968	4733	3884
3874	4684	3843	4998	4047	4522

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

The confidence interval estimate is

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

Answer 1

Here s = 460.38 and n = 12
df = 12 - 1 = 11

α = 1 - 0.8 = 0.2
The critical values for α = 0.2 and df = 11 are Χ^2(1-α/2,n-1) = 5.578 and Χ^2(α/2,n-1) = 17.275

CI = (sqrt(11*460.38^2/17.275) , sqrt(11*460.38^2/5.578))
CI = (367.4 , 646.5)