Answer
Here we have n = 20, x̅ = 18.66, σ = 10.28, df = 19 and Confidence Level = 95%
Using Table C of the book we have t* = 2.093
$σ_{x̅} = \frac{σ}{\sqrt n} = \frac{10.28}{\sqrt 20} = 2.3$
Lower Bound = 18.66 - (2.093)(2.3) = 13.85
Upper Bound = 18.66 + (2.093)(2.3) = 23.47
Work Step by Step
Here we have n = 20, x̅ = 18.66, σ = 10.28, df = 19 and Confidence Level = 95%
Using Table C of the book we have t* = 2.093
$σ_{x̅} = \frac{σ}{\sqrt n} = \frac{10.28}{\sqrt 20} = 2.3$
Lower Bound = 18.66 - (2.093)(2.3) = 13.85
Upper Bound = 18.66 + (2.093)(2.3) = 23.47
