Question

Listed below are speeds​ (mi/h) measured from traffic on a busy highway. This simple random sample was obtained at​ 3:30 P.M. on a weekday. Use the sample data to construct a 98​% confidence interval estimate of the population standard deviation. 64 62 62 56 62 53 60 59 60 69 61 68

Answer 1

From given sample,

Sample standard deviation S = 4.4586

Chi square critical values at 0.02 significance level with 11 df = 3.054 , 24.725

98% confidnce interval for is

Sqrt [ ( n - 1) S2 / U ] < < Sqrt [ ( n - 1) S2 / L ]

sqrt [ 11 * 4.45862 / 24.725 ] < < sqrt [ 11 * 4.45862 / 3.054 ]

2.97 < < 8.46

98% CI is ( 2.97 , 8.46)