1. A city bus service claims that the time to complete the route from the zoo...

1. A city bus service claims that the time to complete the route from the zoo to City Hall never varies by more than 2.0 minutes. The times for 18 randomly chosen trips from the zoo to City Hall were recorded and gave a sample mean of 26.6 minutes with a sample standard deviation of 2.25 minutes. Find and interpret a 98% confidence interval for the population standard deviation of travel times. (State any assumptions that you need to make.)

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Expert Solution

Solution :

Given that,

s = 2.25

²_R = ²_/2,df = 33.409

²_L = ²_{1 -} _/2,df = 6.408

The 98% confidence interval for is,

(n - 1)s² / ²_/2 < < (n - 1)s² / ²_{1 -} _/2

17 * 2.25 ² / 33.409 < < 17 * 2.25 ² / 6.08

1.605 < < 3.6648

(1.605 , 3.6648)

orchestra answered 1 year ago

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