The values listed below are waiting times​ (in minutes) of customers at two different banks. At Bank​ A, customers enter a single waiting line that feeds three teller windows. At Bank​ B, customers...

The values listed below are waiting times​ (in minutes) of customers at two different banks. At Bank​ A, customers enter a single waiting line that feeds three teller windows. At Bank​ B, customers may enter any one of three different lines that have formed at three teller windows. Answer the following questions.

Bank A
6.4
6.6
6.7
6.8
7.1
7.3
7.5
7.8
7.8
7.8


Bank B
4.1
5.4
5.7
6.1
6.8
7.7
7.7
8.5
9.4
10.0

Click the icon to view the table of​ Chi-Square critical values.

Construct a 99​% confidence interval for the population standard deviation sigma at Bank A.

Construct a 99​% confidence interval for the population standard deviation sigma at Bank B.