Edmund's Brainteasers
Problem 16
Problem 16: The choir stalls
The choir consists of 3 girls (Ann, Beth, Claire) and 3 boys (Dave, Evan, Fred) who sing every Sunday. The rules are that the girls always sit on one side in the first row of the stalls, and the boys in the first row on the other side. On one Sunday they decide that from that day on they will keep to the rules but sit in a different arrangement every week. For how many weeks can they keep to this decision of sitting in a different arrangement from any they have sat in before?