Question

listed below are speeds (mi/h) measured from traffic on a busy highway. this simple random sample was obtained at 3:30 pm on a weekday. use the sample data to construct a 90% confidence interval estimate of the population standard deviation
64 60 60 57 60 54 59 58 59 69 61 67
the confidence interval estimate is ___mi/h<θ<mi/h
round to one decimal place as needed

Answer 1

variance of the sample=17.51515

n=sample size=12

sqrt((n-1)s^2/chi sq alpha/2) <sigma < sqrt((n-1)s^2/chi sq1-alpha/2)

sqrt(11*17.51515/19.6751)<sigma<(11*17.51515/4.5748

3.1293<sigma<6.4896

3.1<sigma<6.5

the confidence interval estimate is _3.1__mi/h<θ<6.5 mi/h