Brain Teasers
Spirit Search
You are an expert on paranormal activity and have been hired to locate a spirit haunting an old resort hotel. Strong signs indicate that the spirit lies behind one of four doors. The inscriptions on each door read as follows:
Door A: It's behind B or C
Door B: It's behind A or D
Door C: It's in here
Door D: It's not in here
Your psychic powers have told you three of the inscriptions are false, and one is true. Behind which door will you find the spirit?
Door A: It's behind B or C
Door B: It's behind A or D
Door C: It's in here
Door D: It's not in here
Your psychic powers have told you three of the inscriptions are false, and one is true. Behind which door will you find the spirit?
Answer
The spirit lies behind Door D.If the spirit is behind Door A, then both B and D are true.
If the spirit is behind Door B, then both A and D are true.
If the spirit is behind Door C, then A, C, and D are all true.
If the spirit is behind Door D, then the statements on all the doors are false, except for that on Door B. This matches the rules, and therefore, the resort hotel spirit lurks behind Door D.
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Comments
theres a simpler way to solve this problem. if three of the statements are false then if any of the first three are true, it has to be behind door D by default. the other case is the fourth statement is true, which is contradicted by going thru each of the other statements (more than one true).
This one was easy
umm, i am not sure if this was easy or hard, I need to look at this sight when I am awake. =P
Cool, real cool. I was wondering however if the psychic should be the one to guess which was the correct door . If he or she knew three of the statements were false, she would have known which three. That was just a thought. It does not take away anything from your enjoyable teaser. Keep them coming.
I'm the retard........well at least i don't like IRON MAIDEN
dif spin on old riddle. too easy
It's cute and I enjoyed it, thanks.
Good teaser. Enjoyed it very much.
easy....question though..if u have pyschic powers...cant u just tell which door it is behind??? j/w 
It was Awsome!! 
cool one! 
im not good at this kind of stuff 
I liked this one a lot - though I read it backward (one false and three true). Anyway - a good puzzle. Thanks
ummm, is it if Door D is the one, then inscription on Door b is true???
I knew that it would be easy, but still couldn't get it. I'ts a favorite for sure, I enjoy this kind of teaser.
it was a good teaser, all about logic. It reminded me of that thing with the two samurai, or whatever.
And thundrax, it doesn't say that the door has to be true to have anything behind it.
And thundrax, it doesn't say that the door has to be true to have anything behind it.
good one and easy i actually got it
i enjoyed this one. it was kinda easy but fun. i rearly can solve the teasers so i liked this one alot.
This was a nice little logic problem. Unfortunately, my reasoning had a flaw in it. Congrats, you stumped me! 
So simple. I got this one in at least 45 seconds, but it was fun!
Very easy but still cute.
that was awesome! very easy (as many others have said) but still quite enjoyable to figure out! i like!
I liked this one alot!! very fun to do
this was easy, but fun
that was weird
this one was pretty easy, but i still ejoyed it a whole lot!
this was a nice riddle. it was kinda of tricky though.
Feb 04, 2005
I enjoyed this one and I thought it was well written!
it was siple i got ot right a way
the only reason why i got it was because i thought it said 3 were true and 1 was false, so i assumed, and that's how i got left over with door d. 
. i'm pretty sure i would've got it anyway. . real cute.
. i'm pretty sure i would've got it anyway. . real cute. 
Easy but fun. Good job. There's a fine balance between easy and dopey, but you achieved a simple teaser that was still good.
XIE XIE NI! (THANK YOU)
IT WAS EASY, BUT IT MADE ME THINK FOR A MINUTE.
TKS AGAIN.
IT WAS EASY, BUT IT MADE ME THINK FOR A MINUTE.
TKS AGAIN.
or just look behind each door
great teaser anyway
great teaser anyway
Good teaser. Made you think and reason it out.
A gasser!
Interesting logic teaser. Fairly simple - got it! Thanks for making us think a bit.
Good job - but I couldn't get it. Thanks.
tricked me at first. good one
huh
L TSA Fun. Thanx!
TSA Fun. Thanx!
BTW, I don't usually like the logic puzzles, but this one has entered my Hall of Faves!
That was agreat teaser! The only reason I got it though was because I thought that "D" was the obvious one, because it said"It's not in here."
Good simple logic often makes a good teaser. Good job.
The easiest analysis is as follows: The statements on doors A & B are mutually exclusive and together describe all possibilities. Thus, one of them must true. Therefore C and D must both be false. Clearly if D is false, then that's the door you're looking for.
Octavian: I was about to say the same thing, but I think you worded it better than I could have. You sound like that guy from The Princess Bride.
This was easy.....but it was also very enjoyable.
Unfortunately today I'm not thinking very logically so this one went right over my head. Made a lot of sense to me AFTER I read the answer. Great job!
this one was very tricky..which i guess was your point...LOL...i got it right only becaused i guessed not because i used logic...LOL
I thought it was tricky and awesome. i liked it, its going into my faves.
I LOVED it!! =0] my favorite so far!!!!
loved it!! took me awhile tho... although, couldnt you just look behind each door? i guess that kinda defeats the purpose tho huh? w/e. it was a great teaser.
although, couldnt you just look behind each door? i guess that kinda defeats the purpose tho huh? w/e. it was a great teaser. 
Dude... Talk about twisting my brain around and confusing me. I had to read it like, 6 times b4 i finally figured out what it meant. I kinda feel dumb when that happens ... but, c'est la vie!
I had to read it like, 6 times b4 i finally figured out what it meant. I kinda feel dumb when that happens ... but, c'est la vie! Octavian- Thank you for saving me the trouble of trying to say that. Good teaser!
i only got it because Door D said its not here....so i assumed that it was there...
I guessed d, but that is not why. That confusing. But I liked it ok. 
I guessed d, but that is not why. That confusing. But I liked it ok.
I seriously got it right! WOW! It's just a trick question though, but AWESOME TEASER!
I GOT IT YAY
it was fun and easy
i thought that was quite entertaining and i still have to go back and figure it out but i love a challenge way to go
way to go
WHAT??????????????? 
I didn't get it...
I got it, but it was easier to me because on the queen mary ghost tour they made us do that in the haunted dressing room, and i got it!! Great Teaser!
BOO!
Yes ,a great teaser.
I got it.
Yes ,a great teaser.
I got it.
FUN BUT EZ
That was a good one! I got that one !!!!!!!!!!!
I got that one !!!!!!!!!!!
Easiest way to solve - one of the statements 1 & 2 got to be true (both can't be false simultaneously)
Thus, statement 4 is false and its behind D.
Thus, statement 4 is false and its behind D.
i just read it - analysis made by me was already made by some one else and posted
this is a great teaser, and I enjoyed "trying" to solve it. I must be very logical, because I can never solve a logic teaser. when I see the answer, I think that I should have been able to solve it. it sees so easy when I know the answer. and YES I used to be blond, now I'm gray and white. keep up sending in logic teasers. I may get lucky and solve one.. :
:
ok you got me ---at first i had this big long comment arguing that the answer could be door- A --til i re-read yr answer ---so you win...
thanks for the brain work-out today ...i'll be-thinking it over while i'm stuck in traffic due to the on coming snow and ice... careful driving, gators.....
later gators
thanks for the brain work-out today ...i'll be-thinking it over while i'm stuck in traffic due to the on coming snow and ice... careful driving, gators.....
later gators
Well written!!
This is still a great logic teaser. Got it right this time but it did take a minute to think it thru.
These have got to be the best types of teasers. I just love them. It takes me some time to figure out the answer but I did it. I really love logic teasers. Great job!!! Great teaser!!! Going to go to my faves for sure.
yawn
I couldn't get enough coffee into my brain to even begin! So much easier to click "Show Answer."
Too much thinking for me this early! Good job though.
I would just open the door.........
I would just open the door.........
Good one, but I thought it was behind C.
A Totally Awesome teaser! Not too tough, yet easy enough to get one going in the morning hours! Keep up the terrific work!
Keep up the terrific work!
That was cute! I often wonder how the logician can know what's true and what's not.
To solve it, though, I just used the fact that A and B oppose one another, and not merely contract each other. Therefore, one of those is true, and C and D are false.
I often wonder how the logician can know what's true and what's not.To solve it, though, I just used the fact that A and B oppose one another, and not merely contract each other. Therefore, one of those is true, and C and D are false.
i guessed and still got it right!1
Mar 16, 2007
Check it out....the answer could also be A...Whoever made this brain teaser did not use all their brains.
julesfan, it can't be in A because then both A and D would be true
logical, I'm not
i figured it was behind door C because it could have been trying to tease hence the name brain teaser.
good job!!!!!
good job!!!!!
Fun!!!!!!!!!!!!!!!!!!
I finally got one right and understood it!!! Very clever and fun!!!
Yes, I have no logical abilities! But I liked Octavian's explanation, posted in 2006...I finally understood it then. Good one
But I liked Octavian's explanation, posted in 2006...I finally understood it then. Good one
It's good to know that I'm not brain dead afterall, I got it!
Great teaser!
I usually don't get these, but this one I got!! Yay!! There's hope!!
This was too easy, because I was able to figure it out in less than a minute. I wasn't aware of any "solving facts" until I read Octavian's concisely-worded statement., which will be useful in the future.
I really oughta do more of these Brain thingies!
I really oughta do more of these Brain thingies!
I had this type of question for a math challenge event at school I was the only one that got it.
I was the only one that got it. 
that was easy....but fun...i like the logic behind it....
I thought this was a very cute variant on a familiar type of problem. There were also some very good explanations of how to obtain the answer very quickly, which was also a pleasure to see! I got it pretty easily, kinda like the way octavian described it. And clearly, some of us have seen Princess Bride before!! INCONCEIVABLE!!
I liked this one
I love these kinds of teasers
Process of elimination made this pretty easy. But could be challenging for some who overthink it.
Took me a minute but it was fun!
Yep - I liked this one, even though it was a bit too easy. Obviously statement A or B had to be true, which means C and D both had to be false. If D is false, it's behind door D.
That was a very simple, but great, logic puzzle by using assumptions and contradictions from those 5 statements. Good Job.
Good Job.
BOO!!!
It was too easy!! It's a child's game. No matter what the other choices were.. it's always behind the one that says it's NOT here. Didn't you learn anything as a kid.???
shut up stupid people, i u really dont like this riddle just keep it to yourselves. there's no point in making other people feel bad jut because you do. 
. also the whole point of log puzzle is that if you thik logically YOU SHOULD BE ABLE TO FIGURE IT OUT!!!
*ahem* I PERSONALLY LOVED THIS TEASER. if you can't respect that then maybe YOU'RE the one who needs to grow up. If I can figure that out and I'm not even ourteen years old than you should take the time to use your brain (if you even have one) and THINK.
A big thank you to everyone who posted a positive comment, that is why you have good karma.
. also the whole point of log puzzle is that if you thik logically YOU SHOULD BE ABLE TO FIGURE IT OUT!!!*ahem* I PERSONALLY LOVED THIS TEASER. if you can't respect that then maybe YOU'RE the one who needs to grow up. If I can figure that out and I'm not even ourteen years old than you should take the time to use your brain (if you even have one) and THINK.
A big thank you to everyone who posted a positive comment, that is why you have good karma.
sorry about the typos
i=if
jut=just
log=logic
i=if
jut=just
log=logic
Beyonce--even though what you said about the criticism may have some truth to it, the way you said it was just as bad or worse as those whom you were criticism. If you want to scold someone for a behavior, than you must demonstrate a better behavior. My problem with this site is the lack of respect for other people's opinions.
Even though this teaser was not my favorite type, I respect the opinion of those who enjoyed it. You can't plaese everyone all the time.
Even though this teaser was not my favorite type, I respect the opinion of those who enjoyed it. You can't plaese everyone all the time.
my typos- criticize instead of criticism and then instead of than.
I mean "criticizing" Sorry!
I did it the easy way. Either Door A or Door B was telling the truth, but not both. Therefore, C and D were both lying, meaning D was lying, so it was D.
Simple, easy, fun.
I never ever get these kind of puzzles. Even after explanations they do not make sense to me. I am just a dummy, I guess.
If you unscramble your brain,this is very easy. Also this one has been repeated to many times. I'm sure HABS wiil agree with me.
@Babe Don't worry I am totally with you. I did finally get it, but only after going through the process of elimination AFTER I had already seen the answer
I love logic problems. This one was kind of easy, but still a good one.
Come now cutebug the teaser is only 10 years old. I do in fact agree. While at first glance it may have seemed complicated as soon as you began to eliminate statements, it became quite easy. IT may have taken me 90 seconds
I do in fact agree. While at first glance it may have seemed complicated as soon as you began to eliminate statements, it became quite easy. IT may have taken me 90 seconds
So many players complain that teasers are old - I have been enjoying Braingle for several years now, and seldom run across one I have done before - There are constantly new people joining us that should have a chance to enjoy these that have been used in the past. You all should broaden the pot of choices by writing new ones to add to the collection (Yes, one of these days I plan on doing that!)
EZ but fun
Great answer! Here is another version of the same answer!
These types of teasers are pretty common
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