user: Question: What episode has 7.8 million viewers?
Columns: ['Episode', 'Broadcast date', 'Run time', 'Viewers (in millions)', 'Archive']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['" Episode One "', '19May1973', '25:55', '9.2', 'PAL 2" colour videotape']
SQL:

assistant: SELECT "Episode" FROM "Table" WHERE "Viewers (in millions)" = '7.8';