问一道英语逻辑推理题

题目

问一道英语逻辑推理题
There are 90 people in a group,and among them at least one tells lie.If there is at least one telling truth between two people at random of these people ,then do you know how many people are telling lies?

答案

答案应该是 one
因为这道题说,随机在90人中抽取2个人,这2个人中至少有1个要讲真话.
根据题意,哪怕这些人中有2个说谎的,那么随机抽取2个人的话,就很可能抽到2个都说谎的人,就和题目中“这2个人中至少有1个要讲真话”不符了.
所以,说谎的人至多是一人（也就是1人或0人）,又因为题目的前提是“90人中至少有一人说谎”,答案就是一个人了.