Braingle: 'Vacation!' Brain Teaser

Vacation!

Logic puzzles require you to think. You will have to be logical in your reasoning.

Puzzle ID:	#39000
Fun:	(2.99)
Difficulty:	(2.17)
Category:	Logic
Submitted By:	grilledcheese

A vacationing family sitting around the campfire has the following conversation:

1. Father: What day is it? I am sure it isn't Tuesday, Wednesday or Thursday.
2. Mother: Well that's not very helpful dear. Besides yesterday was Friday.
3. Father: No, now that I think about it, yesterday wasn't Friday, tomorrow is Friday.
4. Jon: The day after tomorrow is Thursday.
5. Meg: You are nuts. Tomorrow is Thursday.
6. Mother: Actually, it's probably Thursday today.
7. Jon: All we know for sure is that it wasn't Sunday yesterday.

If only one statement above is true, what day of the week is it?

Answer

Number each person's statement and write down the list of days that it could be according to each statement.

1. Monday, Friday, Saturday, Sunday
2. Saturday
3. Thursday
4. Tuesday
5. Wednesday
6. Thursday
7. Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday

The only day mentioned one time is Monday. Therefore it must be Monday, otherwise one of the other statements would be true.
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Comments

CatatKHOP Oct 29, 2007	WOO! I got it I'm a very lucky guesser
al111 Oct 29, 2007	It's a bit easy but well done very interesteresting the way you used people instead of just numbering the staments like: 1.Yesterday wasn't friday SO THANKS I RATE IT 9/10!
breathesunshine Oct 30, 2007	Fun teaser!
(user deleted) Nov 02, 2007	It was kind of Silly. But interesting nonetheless!
Lady_Lani Nov 05, 2007	clever!
scallio Nov 08, 2007	Great teaser!
hadalique Dec 04, 2007	fun teaser i actually got it right
coolguy5678 Dec 31, 2007	I'd think that the inclusion of "probably" in statement 6 would make that statement useless, because if that is the true statement, it doesn't necessarily mean that it is Thursday, it just probably is. This doesn't affect the answer though, and it's a good teaser.
xlrfreak Dec 31, 2007	it was fun and i got it right
ripple716 Dec 31, 2007	Nice one!
wandering_goat Dec 31, 2007	Very nice. I misread the last statement as saying it was Sunday for some reason, which screwed up my answer.
wandering_goat Dec 31, 2007	Whoops, I meant I read it as saying that it isn't Sunday TODAY.
jimbooth019 Dec 31, 2007	Good teaser. I got it but had to work at it a while. thanks!
slamherhard Dec 31, 2007
maldrac Dec 31, 2007	Ummm I have a problem with this... 1. it isn't Tuesday, Wednesday or Thursday. (meaning it could be Monday today) 7. it wasn't Sunday yesterday. (meaning it could be Monday today)
coolguy5678 Dec 31, 2007	It wasn't Sunday yesterday = it ISN'T Monday today
bradon182001 Dec 31, 2007	I agree with Jimbooth. Good teaser, especially for a Monday morning.
ppk02042006 Dec 31, 2007	huh
FatHead Dec 31, 2007	And to think I did it the hard way!
(user deleted) Dec 31, 2007	If you run through the arguments Wednesday works aswell. Clue number 7 is true and all the others are false...
twogross Dec 31, 2007	good one for hermione, but I'm Ron..
kratsg Dec 31, 2007	I kinda like this one. I just went on the idea of this: If (1) is true, that means (2) is false, not Saturday, (3) is false, not Thursday, (4) is false, not Tuesday, (5) is false, not Wednesday, (6) is false, not Thursday, (7) is false, not Sunday Tuesday Wednesday Thursday Friday Saturday. Which eliminates all except Monday. Make another one, but with days of the month :-D
dancerchick Dec 31, 2007	I just looked at the last thing someone said and I am just like, Monday. I am so good. good teaser grilledcheese!
saites2001 Dec 31, 2007	@runescaper: If clue 7 is true, then clue 5 is false. If 5 is false, then tomorrow is not Thursday. If tomorrow is not Thursday, than today is not Wednesday.
shawneeo Dec 31, 2007	I liked it, but... I think there's a loophole somewhere. I have to go through it again. I'm sorry to say that when i don't know exactly, but I have a feeling that there's a leak somewhere... I actually got Wednesday, like the person above said, so I'm wondering... anyway, I'm probably wrong, I know that, but I will check it out and if I'm right I'll post again, otherwise, I'm wrong. But either way, I still enjoyed it very much, and I hope you do some more similar ones. Really the best ones are the ones where you have to keep checking it because it's a REAL TEASER!
2ndhandrose Dec 31, 2007	I may have lost it. But which sentence mentioned Monday at all. It says Monday was only mentioned once?? Have I lost it? Don't get it at all!! Sorry.
2ndhandrose Dec 31, 2007	Me again, which is the True statement. I am lost on this one. Have had lots of tea. Happy New Year All!!!!
2ndhandrose Dec 31, 2007	Rose again. Which is the only true statement?? Is it in the figuring out part? I just don't get it. Anyway, HAPPY NEW YEAR ALL !!!!
2ndhandrose Dec 31, 2007	Sorry, the 2nd posting didn't show up right away. So thought it didn't take & wrote again. Did not mean to post 3 times Now it is 4. Sorry again
MattsAli1108 Dec 31, 2007	7. All I know for sure is it wasn't Sunday yesterday. Isn't that saying it can't be Monday? Confused.
mondayschild59 Dec 31, 2007	Well you didn't get me that time. I read that sucker through three times. The only answer I came up with was Monday. Thanks for the teaser. Very fun. Monday~
CatsAreCute Dec 31, 2007	Great teaser! TAKE A CALENDAR!!!
nerdyiscool Dec 31, 2007	The only true statement: I'm confuddled. Know how it feels, though! HAPPY NEW YEAR!!!
petebob796 Dec 31, 2007	Bit easy but fun. You only really need to look at No. 7 as this covers every day but monday.
GrandmaB Dec 31, 2007	SOMEBODY, Get those people a calendar!!!! (Tricky comprehension problems are not my forte.)
Madelulabelle Jan 01, 2008	Sorry, couldn't get this one, didn't even try, not at my present stage of recovery (from last night's partying!). But still, very clever teaser, makes me wish I had waited till tomorrow to check my email!!!
dogg6pound9 Jan 02, 2008	i didnt get it either... did exactly what the answer said and labeled the possibilities... then read statement #7 and said well it cant be monday according to that statement... but it is monday... how???
vlerma Jan 03, 2008	What a vacationl. Any day is a good day but Monday so it had to be Monday. Great teaser there grilledcheese.
zaya Jan 04, 2008	Fantastic teaser, even though I missed it
myhalcyondaze May 14, 2008	This teaser has a fallacy. Either clue 2 or 3 must be true, because they contradict each other if both are false. Read carefully! Clue 2 states yesterday WAS Friday (i.e. it is Thursday). Clue 3 states yesterday WASN'T Friday (i.e. it is NOT Thursday). It cannot be both Thursday and not Thursday (if both were false). However, having either clue 2 or 3 as true is contradicted by other statements being false. Clue 2 cannot be true because then clue 1 is also true (if it is Saturday, that is also not Tuesday, Wednesday, or Thursday). Clue 3 cannot be true because then clue 6 is also true (they both imply that it is Thursday). However, as another commentor stated, the word "probably" makes clue 6 useless because it cannot be true or false. If the phrase "yesterday wasn't Friday" is removed from clue 3, I would agree that the answer is Monday.
Jgomez7830 Oct 31, 2010	Fun but hard! Good job!
Malisa Dec 31, 2010	Nice one!
patiencewithaP Dec 31, 2010	Fun! Took a bit of thinking but was a great teaser!
wordmama Dec 31, 2010	I had a sense that it was Monday due to its scarcity, but I couldn't really put my finger on the exact reasoning. I had to check out the explanation a couple of times before I could go 'yes, I see.' Phew!
sunnybonghits Dec 31, 2010	Very nice
dani4w45t Dec 31, 2010	this was a good teaser but as some have pointed out, the wording is problematic in some places. The correct, "one true statement" is statement 1. However, the way the clues are written, statements 2 and 3 contradict each other so one must be true and one must be false. Unless you read it as saying, since the father comes directly after the mother, "you are wrong mother to say yesterday was friday (= yesterday wasn't friday) in fact, tomorrow is friday; so that the only statement he is asserting in clue three is there tomorrow is friday. To have the father say "he is sure..." in clue one for it to be false means "he isn't sure" not that it is definitively not the case. Likewise, clue six, the falsification of "probably" is "probably not" not definitively not. So, good teaser, it was creatively written but in the future use more precise language. Best!
ajboq132 Jan 03, 2012	only one statement should be true.. but when the Father said that it wasn't Tue Wed, or Thurs. if that was true, then it should be Mon, Fri, Sat, or Sun. And the Mother's statement states that it was saturday that day. so both of their statements support each other... so both of them should be lies if there should only be one statement that is true.
princess2007 Feb 23, 2013	Honestly, I found this pretty annoying because of the way its written. Statement 3 says: "No, now that I think about it, yesterday wasn't Friday, tomorrow is Friday." If 1 is true, then 3 is false. Statement 3 countered is "Yesterday WAS Friday, tomorrow IS NOT Friday."- which would make it Saturday today, not Monday. Leading to an impossible event. When you say a statement is false, the WHOLE statement is false. I think this teaser needs to be rewritten. I appreciate the effort but to be honest, I don't like this one at all. Not because I didn't get it, but because I think it's wrongly worded.