CREATE TABLE table_1847180_3 (vacator VARCHAR2, date_of_successors_formal_installation VARCHAR2)

Who vacated his post when his successor was formally installed on May 11, 1966?
SELECT vacator FROM table_1847180_3 WHERE date_of_successors_formal_installation = "May 11, 1966"
SELECT "vacator" FROM "table_1847180_3" WHERE "May 11, 1966" = "date_of_successors_formal_installation"