Three students share a house. Having better things to do than clean house, they hire someone to come in and clean once each week. How should they share the costs of the housekeeper? One simple solution is to share the cost equally. Suppose, however, that one student’s bedroom is twice as large as each of the other students’ bedrooms. The second student has a small bedroom and uses the house only four days per week. The third student uses the house all week, has a small bedroom, and is generally acknowledged to be the cleanest of the three. Sharing the cost equally is simple, but is it fair?