A group of campers have been on vacation so long, that
they've forgotten the day of the week. The following
conversation ensues.
Darryl: What's the day? I don't think it is Thursday, Friday or Saturday.
Tracy: Well that doesn't narrow it down much. Yesterday was Sunday.
Melissa: Yesterday wasn't Sunday, tomorrow is Sunday.
Ben: The day after tomorrow is Saturday.
Adrienne: The day before yesterday was Thursday.
Susie: Tomorrow is Saturday.
David: I know that the day after tomorrow is not Friday.
If only one person's statement is true, what day of the week is it?
Tracy's statement that the day of the week is Monday agrees with Darryl's statement that the day of the week cannot be Thursday, Friday, or Saturday and therefore cannot be true.
Melissa's statement that the day of the week is Saturday agrees with Adrienne's statement that the day of the week is Saturday and also cannot be true.
Ben's statement that the day of the week is Thursday, and Susie's statement that the day of the week is Friday is only true if Darryl's statement is false. But David's statement that the day of the week is not Wednesday would also hold for both of these days, and therefore cannot also be true.
If David's statement that the day of the week is not Wednesday is the only true statement this would mean that the only other remaining days of the week not already ruled out are Sunday and Tuesday--which are both in agreement with Darryl's statement. Therefore Wednesday is the day of the week, and Darryl's statement is the only correct statement.
(NOTE: I like D.J.'s solution the best; so much more simple than mine.)
Much cruder solution:
