user: Question: How many people were surveyed in the poll from June 30, 2010?
Columns: ['Poll source', 'Date(s) administered', 'Sample size', 'Margin of error', 'Jerry Brown (D)', 'Meg Whitman (R)']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Rasmussen Reports', 'January 14, 2009', '500', '±4.5%', '40%', '38%']
SQL:

assistant: SELECT "Sample size" FROM "Table" WHERE "Date(s) administered" = 'June 30, 2010';