CREATE TABLE table_13621 ("School" TEXT, "Location" TEXT, "Mascot" TEXT, "Enrollment" FLOAT, "IHSAA Class" TEXT, "# / County" TEXT)

What is the enrollment at the school with IHSAA class A and where mascot is the Vikings?
SELECT "Enrollment" FROM table_13621 WHERE "IHSAA Class" = 'a' AND "Mascot" = 'vikings'
SELECT "Enrollment" FROM "table_13621" WHERE "IHSAA Class" = 'a' AND "Mascot" = 'vikings'