Answer
95% CI for $μ_d$: $29.55\lt μ_d\lt35.85$
Since the interval does not contain $μ_d=0$, reject the null hypothesis.
There is enough evidence to conclude that braking distance on wet pavement differs from dry pavement.
Work Step by Step
$H_0:~µ_d=Wet-Dry=0$ versus $H_1:~µ_d=Wet-Dry\ne0$
In MINITAB, enter the Wet values in C1 and the Dry values in C2.
Select Stat -> Basic Statistics -> Paired-t
Select "Each sample is in a column". In "Sample 1" enter C1 and in "Sample 2" enter C2
Click Options. In confidence level enter 95. In Hypothesized difference enter 0. In Alternative hypothesis select difference $\ne$ hypothesized difference. Click OK.
Click OK.
