There are 20 rooms at the Finite Hilton Hotel. 9 rooms are occupied by 2 people each; 7 rooms are each occupied by a single person; and 4 rooms are vacant.
If you talk to a random guest of the hotel at breakfast, then, assuming that person is equally likely to be any of the guests at the hotel, what is the expected number of people staying in that person's room (including him- or herself)?
I don't know how to approach this. There are 25 people in 20 rooms, but i don't know if the answer is 1.25 expected people to be in that room.