CREATE TABLE table_55423 ("Date" TEXT, "Visitor" TEXT, "Score" TEXT, "Home" TEXT, "Decision" TEXT, "Attendance" FLOAT, "Series" TEXT)

What was the attendance of april 17?
SELECT SUM("Attendance") FROM table_55423 WHERE "Date" = 'april 17'
SELECT SUM("Attendance") FROM "table_55423" WHERE "Date" = 'april 17'