Twelve different video games showing substance use were observed and the duratio

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

Explanation / Answer

Solution:

From the given sample data, we have

Sample size = n = 12

Sample standard deviation = S = 0.387139

Confidence level = 80%

Degrees of freedom = n – 1 = 12 – 1 = 11

Lower Chi square value = 5.5778

Upper Chi square value = 17.2750

Confidence interval formula is given as below:

Sqrt[(n – 1)*S^2/upper chi square value] < < Sqrt[(n – 1)*S^2/lower chi square value]

Sqrt[(12 – 1)*0.387139^2/17.2750] < < Sqrt[(12 – 1)*0.387139^2/5.5778]

0.3089 < < 0.5437

0.3 sec < < 0.5 sec

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