Question

core: 0 of 2 pts 12 of 13 (9 complete) HW Score: 54.76%, 23 of 42 pts 7.4.13 Question Help 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 95% 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. 4,381 4,298 4,733 3,904 4,711 4,465 4,152 4,133 4,810 4,705 5,021 3,964 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.) | sec.

Answer 1

> x=c(4381,4733,4711,4152,4810,5021,298,3904,4465,4133,4705,3964)
> x
[1] 4381 4733 4711 4152 4810 5021 298 3904 4465 4133 4705 3964
> S2=var(x) ### Sample variance
> S2
[1] 1565452
> n=length(x)##sample size
> n
[1] 12
> a=0.05##level of significance
> ql=qchisq(1-(a/2),(n-1)) ###upper chisquare value
> ql
[1] 21.92005
> qu=qchisq((a/2),(n-1)) ###lower chisquare value
> qu
[1] 3.815748
> LCL=sqrt(((n-1)*S2)/ql)##lower confidence limit
> LCL
[1] 886.3301
> UCL=sqrt(((n-1)*S2)/qu)##upper confidence limit
> UCL
[1] 2124.352
> CL=c(LCL,UCL)
> CL
[1] 886.3301 2124.3517
>