The correct preposition here is "on," because when describing the position of a door relative to a person, it is most natural to say "the door closed on him."
Thus, the correct preposition is "on," making the sentence: "The door closed on him."
Arun’s present age in years is 40% of Barun’s. In another few years, Arun’s age will be half of Barun’s. By what percentage will Barun’s age increase during this period?