Michael tells the truth on Sunday, Monday, Wednesday, and Friday, and lies on Tuesday, Thursday, and Saturday. Michelle tells the truth on Sunday, Tuesday, Wednesday, and Saturday, and lies on Monday, Thursday, and Friday. One day, they make the following statements.

Michael:Today is Sunday.
Michelle:Today is Wednesday.

What day is it?

As Michael and Michelle have not affirmed the same day, one or both are lying, and thus it could not be the days in which both tell the truth: Sunday and Wednesday. As these are the two days claimed, neither Michael or Michelle can be telling the truth. And, thus, it must be Thursday, as it is the only day in which both tell lies. 

           Su M  Tu W  Th F  Sa
Michael    T  T  F  T  F  T  F 
Michelle   T  F  T  T  F  F  T
                       ^

Posted by Dej Mar on 2013-01-31 11:48:32