A mailman delivers 90 letters to an office, 50 of which are supposed to go to the Accounting Department and 40 of which are supposed to go to the Marketing Department. However the mailman finds that the exact address on 2 of these letters have been washed away by a sudden downpour which caught him on the way into the office. Needless to say, a sudden downpour washing away addresses is a completely random event. The mailman takes a chance and delivers both letters to the Accounting Department. What is the probability that

(i) he delivered both letters to the wrong department

(ii) he delivered both letters to the correct department

(iii) he delivered one letter right and one wrong