Answer

1. Place Category and Region on Columns. 
2. Place Profit on Rows.
3. Select Analysis > Create Calculated Field.
4. Name the calculated field, for example "Reference Line". Enter a calculation similar to the following, then click OK: 

   CASE Category
WHEN "Furniture" Then 10000
WHEN  "Office Supplies" Then 40000
WHEN "Technology" then 30000
END

5. Place Reference Line on Detail.
6. On the Marks card, Right-click Reference Line and select Measure > Average.
7. On the Analytics tab, select Average Line and then Pane. 
8. Right-click your new reference line and select Edit. Select and enter the following, then click OK:
   • Scope: Per Pane
   • Value: AVG(Reference Line), Average
   • Label: Custom, Goal