user: Question: What is the class for the ERP W of 500?
Columns: ['Call sign', 'Frequency MHz', 'City of license', 'ERP W', 'Class', 'FCC info']
Types: ['text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['K224BV', 92.7, 'Kingman, Arizona', 82.0, 'D', 'FCC']
SQL:

assistant: SELECT "Class" FROM "Table" WHERE "ERP W" = 500.0;