Final answer:
In cell R9, the AVERAGE function with structured references can be used to determine the average number of years of post-secondary education by typing =AVERAGE(Table1[Post-Secondary Years]), replacing 'Table1' and 'Post-Secondary Years' with the actual table and column names.
Step-by-step explanation:
To enter a formula using the AVERAGE function and structured references in cell R9, you would typically click on cell R9 and then type:
=AVERAGE(Table1[Post-Secondary Years])
Here 'Table1' should be replaced with the actual name of your table, and 'Post-Secondary Years' should be replaced with the actual name of the column that contains the data for the years of post-secondary education. This formula computes the average by adding all the numbers in the specified column and dividing by the count of non-empty cells in that column.