CREATE TABLE table_47884 ("Poll Source" TEXT, "Dates administered" TEXT, "Democrat: Beverly Perdue" TEXT, "Republican: Pat McCrory" TEXT, "Libertarian: Michael Munger" TEXT, "Lead Margin" FLOAT)

What is the lead margin for McCrory when he has 49%?
SELECT "Lead Margin" FROM table_47884 WHERE "Republican: Pat McCrory" = '49%'
SELECT "Lead Margin" FROM "table_47884" WHERE "Republican: Pat McCrory" = '49%'