Question

6.4.23-T Question Help The waiting times in m es of a random sample of 22 people bank have a sample standard deviation of 31 minutes Construct a confidence interval for the population variance b ovel of confidence. Assume the sample is from a normally distributed population and the population standard deviation Use a What is the confidence interval for the population walance ? L D (Round on decimal place as needed) Emer your answer in the cold and then cho Check Answer Semang Check Answer # Type here to search 0 0 A SOM 1 2 3 4 5 6 7 8 9 0

Answer 1

Ans:

Given that n=22

s=3.1

confidence level=0.99

alpha=1-0.99=0.01

alpha/2=0.005

critical chi square values:

CHIINV(0.005,21)=41.401

CHIINV(0.995,21)=8.034

99% Confidence interval for population variance:

lower limit=(22-1)*3.1^2/41.401=4.9

upper limit=(22-1)*3.1^2/8.034=25.1

99% Confidence interval for population standard deviation:

lower limit=sqrt((22-1)*3.1^2/41.401)=2.2

upper limit=sqrt((22-1)*3.1^2/8.034)=5.0