CREATE TABLE table_27987623_4 (rank_timeslot_ VARCHAR, airdate VARCHAR)

what is the total rank on airdate march 30, 2011?
SELECT COUNT(rank_timeslot_) FROM table_27987623_4 WHERE airdate = "March 30, 2011"
SELECT COUNT("rank_timeslot_") FROM "table_27987623_4" WHERE "March 30, 2011" = "airdate"