Roswellmike,
In this simple example, there are two sets of data. The first set of data
is grocery store expense and the second set of data is the average grocery
store expense.
Expense Avg. Expense
meat $152 $240
lettuce $242 $240
carrots $321 $240
apples $245 $240
Now you can build a regular clustered column chart first and create the
average line from that chart second.
Start column 1 in cell A2, column 2 in cell B1 (Expense), and column 3 in
cell C1 (Avg. Expense). Cell A1 should be blank. Add the data into your
spreadsheet. When complete, the data should span the range A1:C5.
Put your curser in cell A1 and go to the chart wizard. In the standard
types tab, choose the Column -> Clustered Column option. Hit the Next key
and go through the prompts until finished. When complete, you should have a
chart with two series consisting of bars - your original data and the average
of that data.
To create the average line, click once on any one of the average bars
(clicking once on any one of the average bars should select the entire
average series). Right-click your mouse, select "Chart type . . ." in the
menu, choose a regular Line chart, and then hit the OK button. You should
get a line consisting of the average values going across the first series of
bars.