Who is Mrs Robinson?

Answer 1

From the Simon & Garfunkel Mrs. Robinson wiki page:

"In the film The Graduate, listless recent college graduate Benjamin Braddock has an affair with an older married woman, Mrs. Robinson. The song as it appears in the film is different from the familiar hit single version, as only the chorus of the song appears multiple times throughout the second half of the film. It was only later on that Paul Simon and Art Garfunkel re-recorded the song by employing additional lyrics to form the hit single."