30个旅客同乘一船，超载航行，途中风浪大作，危险万状。船长告诉大家，只要将船舱一半的乘客投入海中，其余人方能幸免于难。无奈，大家只能赞成这个方法，并议定30个人围成

一圈，由第一个人数起，挨次报数，每数到第9人，便把他投入海中，如此循环地进行，直至剩下15个乘客为止，问哪些位置是将被投下海的位置？-30 passengers with a boat ride, sail overloaded, the way waves masterpiece perilous. Captain tell you, as long as half of the passenger cabin into the sea, the rest can only survive. But unfortunately, we can only favor this approach, and agreed to 30 people surrounded

Circle, starting　the first personal number, number off one by one, every few months to 9, put him into the sea, so cyclically, until the remaining 15 passengers so far, and asked what the position is to be dropped Sea location?