The 
Scenario Chart for Mortgage Interest Rate shows you what the interest rate on the mortgage is in a Scenario.
Here is an example of buying rental properties, but where the mortgage interest rate has been changing over time so each one has a different mortgage interest rate. This is really a Chart of Mortgage Interest Rate for 
Properties and not for the whole Scenario.
What Should I Use For Mortgage Interest Rates When Modeling The Future?
It is impossible to predict exactly what mortgage interest rates will do in the future, but it might help to look at what interest rates have done in the past to get a feel for what they may do in the future.
The following is a chart showing historical interest rate data. These are NOT mortgage interest rates; those tend to be a little higher than what is shown below.
Additional Information About Scenario Charts
If you're interested in learning more about the Scenario Charts in the Real Estate Financial Planner™ check out these resources below.