15名基督教徒和15名异教徒同乘一船航行，途中风浪大作，危机万分，领航者告诉大家，只要将全船的一半人投入海中，其余人就能幸免。大家都同意这个办法，并协定者30人围成一圈；由第一个人起报数，每数至第9人便把他投入海中，下一个接着从1开始报数，第9人又被投入海中，依次循环，直至剩下15人为止。问题是如何排法使投入海中的人全为异教徒？-15 Christians and pagans 15 vessels with one by the way, big waves, extreme crisis, leader told everyone that as long as will be half the person boat into the sea, and the remaining person will be able to escape. We all agree that this approach, and agreements were 30 form a circle　from the first reported from a few individuals, the number to 9 for each person put him into the sea, then from the next one to start off, 9 people have been invested in the sea, followed by cycle, until the remaining 15 people so far. The question is how to row Act so that the person into the sea all infidels?