Answer
$z=-1.209$
7.8 g/dL is 1.209 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.
$x̅=10.08$
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.
$s=1.886$
$z=\frac{x-x̅}{s}=\frac{7.8-10.08}{1.886}=-1.209$
