Answer
There is enough evidence to conclude that there is a linear relation between Horsepower with Miles per Gallon.
There is not enough evidence to conclude that there is a linear relation between Engine Size and Curb Weight with Miles per Gallon.
Work Step by Step
With the results obtained in item (b), in MINITAB:
1) $H_0: β_1=0$ versus $H_1: β_1\ne0$
$t_0=1.43$ with a P-value $=0.187\gtα=0.05$. Do not reject the null hypothesis.
2) $H_0: β_2=0$ versus $H_1: β_2\ne0$
$t_0=-1.03$ with a P-value $=0.332\gtα=0.05$. Do not reject the null hypothesis.
3) $H_0: β_3=0$ versus $H_1: β_3\ne0$
$t_0=-2.50$ with a P-value $=0.034\ltα=0.05$. Reject the null hypothesis.
