Answer
(a) $38,808 to 51,192
Work Step by Step
Here we have n = 25, x̅ = 45000, s = 15000, df = 24 and Confidence Level = 95%
Using Table C of the book we have t* = 2.064
$s_{x̅} = \frac{s}{\sqrt n} = \frac{15000}{\sqrt 24} = 3061.86$
Lower Bound = 45000 - (2.064)(3061.86) = 38,808
Upper Bound = 45000 - (2.064)(3061.86) = 51,192