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 99​% confidence interval estimate of the population standard deviation.

61

60

60

57

60

55

59

58

59

68

58

66

Use the table of​ Chi-Square critical values to find the confidence interval estimate.

Answer 1

	here n =	12
	s2=	13.1742
Critical value of chi square distribution for' 11 df and 99 % CI
Lower critical value χ2L=		2.603
Upper critical valueχ2U=		26.757

for Confidence interval of Standard deviation:
Lower bound =√((n-1)s2/χ2U)=		2.327
Upper bound =√((n-1)s2/χ2L)=		7.461
from above 99% confidence interval for population standard deviation =(2.327<σ<7.461)