CREATE TABLE table_38455 ("Poll source" TEXT, "Dates administered" TEXT, "Roy Barnes" TEXT, "Thurbert Baker" TEXT, "DuBose Porter" TEXT, "David Poythress" TEXT, "Undecided" TEXT)

What was the undecided with Roy Barnes at 47%?
SELECT "Undecided" FROM table_38455 WHERE "Roy Barnes" = '47%'
SELECT "Undecided" FROM "table_38455" WHERE "Roy Barnes" = '47%'