Answer
$z=-0.725$
36.3 miles per gallon is 0.725 standard deviations below the mean.
Work Step by Step
In MINITAB, insert all the values of the table in the column C1.
Select Calc -> Column Statistics
In "Statistic" select "Mean".
In "Input variable" enter C1.
Click OK.
The result for the mean will be given.
$x̅=38.775$
Select Calc -> Column Statistics
In "Statistic" select "Standard deviation".
In "Input variable" enter C1.
Click OK.
The result for the standard deviation will be given.
$s=3.416$
$z=\frac{x-x̅}{s}=\frac{36.3-38.775}{3.416}=-0.725$
