The values listed below are waiting times (in minutes) of customers at two diffe
ID: 3183218 • Letter: T
Question
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. 7.1 7.3 Bank A 6.7 7.8 7.8 6.4 6.6 6.8 7.4 7.8 Bank B 4.2 5.4 5.9 6.3 6.8 7.6 7.6 9.3 0.0 E Click the icon to view the table of Chi- critical values. Square Construct a 95% confidence interval for the population standard deviation a at Bank A. min ank A. (Round to two decimal places as needed.)Explanation / Answer
Confidence Interval
CI = (n-1) S^2 / ^2 right < ^2 < (n-1) S^2 / ^2 left
Where,
S = Standard Deviation
^2 right = (1 - Confidence Level)/2
^2 left = 1 - ^2 right
n = Sample Size
Since aplha =0.05
^2 right = (1 - Confidence Level)/2 = (1 - 0.95)/2 = 0.05/2 = 0.025
^2 left = 1 - ^2 right = 1 - 0.025 = 0.975
the two critical values ^2 left, ^2 right at 9 df are 19.0228 , 2.7
S.D( S^2 )=(0.5314)^2
Sample Size(n)=10
Confidence Interval for varaince = [ 9 * 0.2824/19.0228 < ^2 < 9 * 0.2824/2.7 ]
= [ 2.5415/19.0228 < ^2 < 2.5415/2.7004 ]
= [ 0.1336 , 0.9411 ]
Confidence Interval for sd = [ sqrt(0.1336) < < sqrt(0.9411) ] = [ 0.36551 < < 0.9701 ]
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