Math 130 Spring 2009
Graphing Difference Equations in Excel
Example: Average Daily Petroleum Consumption ’97-‘07
1. Open the Excel Worksheet Diffeq.xls. Notice that the table with our data is already in
cells A2-B13.
2. To make a graph from this table, first select(highlight) the entire table:
3. Select Insert from the Ribbon, then Scatter, then the first option of the third row as
shown here:
4. The plot should appear. You can drag a corner to enlarge or shrink. You can also
move the entire graph if you need to.
5. Now use Excel to find the difference in average daily oil consumption each year. In
other words – find C1998 – C1997, and C1999 – C1998, etc. Store these values in K4-K12 (the
column is already labeled Differences).
Click in cell K4.
Type: an “=” to tell Excel that you are starting a formula.
Then click in cell B4 (which contains C1998 = 74,053).
Type a minus sign (-),
Then click in cell A4 (which contains C1997 = 73,427).
Hit Enter.
Make sure the correct difference appears in cell K4. If it does, then ‘drag down’ through
cell K12. You should see the differences for all years 1998-2007.
6. Since the last difference is negative – we don’t want to include the year 2007 in our
model. So let’s delete it from our graph. Click anywhere in the graph, then highlight
cells A13-B13 (containing the data ’07 and 85,802), then hit your Delete key. This
should remove this point from your graph. Did it?
Excel graphing I Page 1
