Answer
$t_0\lt -t_α$: null hypothesis is rejected.
There is enough evidence to conclude that the repair cost of the car is higher than the repair cost of the SUV.
Work Step by Step
$d_i=(SUV~Damage)_i-(Car~Damage)_i$
$d_1=581$
$d_2=-1221$
$d_3=-3868$
$d_4=-2683$
$d_5=-3686$
$d_6=-2995$
$d_7=2163$
$d ̅=\frac{∑d_i}{n}=-1672.71$
$s_d=\sqrt {\frac{∑(d_i-d ̅)^2}{n-1}}=2296.29$
$H_0:~µ_d=0$ versus $H_1:~µ_d\lt0$
$t_0=\frac{d ̅ }{\frac{s_d}{\sqrt n}}=\frac{-1672.71}{\frac{2296.29}{\sqrt 7}}=-1.927$
$n=7$, so:
$d.f.=n-1=6$
Left-tailed test:
$t_α=t_{0.1}=1.440$
(According to Table VI, for d.f. = 6 and area in right tail = 0.1)
So, $-t_α=-1.440$
Since $t_0\lt -t_α$, we reject the null hypothesis.
