Answer
Conclusion: there is not enough evidence that the mileage from 92 octane is greater than the mileage from 87 octane.
$t_0=1.14$ with a P-value $=0.141$ which is greater that the usual values of α (0.01, 0.05 and 0.1). We will not reject the null hypothesis.
Work Step by Step
$H_0:~µ_d=92~Octane-87~Octane=0$ versus $H_1:~µ_d=92~Octane-87~Octane\gt0$
