100个人做题

来源: 于 2010-06-20 20:08:43 [旧帖] [给我悄悄话] 本文已被阅读：次

A group of 100 people to answer five questions. 81 got right on first, 91 got right on second, 85 got right on third, 79 got right on fourth, 74 got right on fifth.
Question: At least how many people got at least three questions correct?