Answer
(b) 327.92 to 386.08
Work Step by Step
Here, we have n = 8, x̅ = 357, σ = 50
$σ_{x̅} = \frac{σ}{\sqrt n} = \frac{50}{\sqrt 8} = 17.68$
For the 95% confidence interval, we have z = 1.65
Upper Bound = 357 + (1.65)(17.68) = 386.172
Lower Bound = 357 + (1.65)(17.68) = 327.828