Can I add a baseline value to a chart?

[Guest]

I have a chart that shows results of tests taken on different dates to show
improvement. I need to add a baseline to the chart showing the Desired
Result.

 

[Bernard Liengme]

From an earlier reply:
You can add the lines to the chart by using extra data series.
Here is a collection of examples.

http://peltiertech.com/Excel/Charts/RunChtLines.html
http://peltiertech.com/Excel/Charts/AddLine.html
http://tushar-mehta.com/excel/charts/straight_lines/index.html
http://www.andypope.info/charts/averageline.htm