user: Question: What is run time when there were 7.4 million viewers?
Columns: ['Episode', 'Broadcast date', 'Run time', 'Viewers (in millions)', 'Archive']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['" Strangers in Space "', '20June1964', '24:46', '7.9', '16mm t/r']
SQL:

assistant: SELECT "Run time" FROM "Table" WHERE "Viewers (in millions)" = '7.4';