Answer
Lower Bound = 40.227
Upper Bound = 55.773
We can see that the outlier has caused the confidence interval to get wider and the lower bound to shift leftward.
Work Step by Step
Here we have n = 12, df = n-1 = 11, x̅ = 48 and s = 12.233
Confidence = 95%
α = 1 - 0.95 = 0.05, α/2 = 0.025, $t_{α/2} = 2.201$
$E = 2.201 \times \frac{12.233}{\sqrt 12} = 7.773 $
Lower Bound = x̅ - E = 48 - 7.773 = 40.227
Upper Bound = x̅ + E = 48 + 7.773 = 55.773
