Answer
Since we reject the Null Hypothesis (contractor's claim), there is enough evidence to support the councilwoman’s belief that the mean time is greater than 3.2 days.
Work Step by Step
Here we have $H_{o}$: μ = 3.2, $H_{a}$: μ > 3.2, n = 12, x̅ = 4.43, s = 2.148 and α = 0.05
Using the Classical approach:
Using Table VI, we have: t = 1.796
$σ_{ x̅} = \frac{s}{\sqrt n} = \frac{2.148}{\sqrt 12} = 0.62$
$t = \frac{4.43 - 3.2}{0.62} = 1.98$
Since, 1.98 > 1.796, we will reject the Null hypothesis.
