CREATE TABLE table_8559 ("Episode Number" FLOAT, "Air Date" TEXT, "Event 1" TEXT, "Event 2" TEXT, "Event 3" TEXT, "Event 4" TEXT)

What episode had sumo ball for event 3 and the wall for event 4?
SELECT AVG("Episode Number") FROM table_8559 WHERE "Event 4" = 'the wall' AND "Event 3" = 'sumo ball'
SELECT AVG("Episode Number") FROM "table_8559" WHERE "Event 3" = 'sumo ball' AND "Event 4" = 'the wall'