SAT数学考试逻辑推理题解析

例题：
　　Family
　　Numbers of Consecutive
　　Nights
　　Jackson
　　10
　　Callan
　　5
　　Epstein
　　8
　　Liu
　　6
　　Benton
　　8
　　The table above shows the number of consecutive nights that each of five families stayed at a certain hotel during a 14-night period. If the Liu family’s stay did not overlap with the Benton family’s stay, which of the 14 nights could be a night on which only one of the five families stayed at the hotel?
　　A. The 3rd B. The 5th C. The 6th D. The 8th E. The 10th
　　解答：此题只要借助线段，便一目了然了。既然原文说“the Liu family’s stay did not overlap with the Benton family’s stay”，而且两家刚好加在一起正好是14晚，那么不妨将这14晚设为一段长14cm的线段，从6cm处分割：
　　Liu Benton family family︳______ ____︳_________________︳
　　0 6cm 14cm
　　︳________10cm__________︳

　　︳________10cm__________︳
　　上题的解答过程就是利用逻辑推理的过程，由于Jackson family是剩余家庭里呆得时间最长的，所以只要从他家看起即可。该题可以简单转化为一段长10cm的线段在14cm范围内左右移动，要么露出最左面的 0~4cm空间(不包括4)，要么留出最右面的10~14cm(不包括10)。所以没有被 Jackson family所覆盖的只有这两个区间，也就是说只有一家居住的只能是前三天或后三天，答案为A。