an IQ question for all to solve.
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Originally posted by bladez87:A - red
B - red
C see them both red
none of them exit means they unsure of their color.
however all 3 hands are raised, meaning 3 reds or 2reds 1 green.
since 2 reds 1 green would mean both reds know they are red and thus leave the room.
but since none leave until C left, meaning 3 reds and they dont know they have 3 reds until C left.
once A know B is red
or B know A is red
both will know C is green and thus know they are red.
however since A know B and C is red
B know A C red
C know A B red
and none left means C got to be red or else the other 2 would have left.
why? -
i thot reason explaineded liao...
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issit?...then can put the real answer in the first post so tat we noe the correct explanation?Originally posted by kaobeikaobu:i thot reason explaineded liao... 
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he doesnt know what A & B sees, except that they see a red hat (or 2)Originally posted by huiz:din totally go thru other posts....but issit:
A, B & C all think their own hat is green coz they all see 2 red hats.
A says his hat is green but he is wrong.
Again B says his hat is green & he is oso wrong.
C then thinks:
- A muz hav seen B & C's hat is red, so he thinks his own color is green.
- B oso sees A & C's hat is red, so he guesses his color is green.
but both A & B is wrong as C can see for himself they are both red hats.
A & B's answers tell C tat they both saw red hats.
overlapping both wat A & B sees, C is clearly wearing red so tat is how he derive his guess.
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all these assuming they all think there r 2 red & 1 green hats since they r told there r green & red hats. lets see.... -
Explanation:
For everyone to raise their hands, the only combinations possible are either 2 red hats & 1 green hat OR 3 red hats.
Basically, since these are the only 2 possible combinations, anyone who sees a green hat can walk out knowing that his is a red hat.
If, however, they saw 2 red hats, it is always possible for theirs to be a green hat.
Since neither A & B saw a green hat, they did not walk out, as it was always possible that theirs could be green.
C sees them wondering, and he knows that his has to be red hat, for if his was a green hat, neither A or B would hesitate to move out.
P.S: Chances are, by this logic, if C walks out, A & B are likely to think that theirs is red, as they might believe that C walked out because C saw a green hat. Since A & B can see that each others hats are red, they'd think that theirs is green. -
if i can edit the first post....Originally posted by huiz:issit?...then can put the real answer in the first post so tat we noe the correct explanation? -
i was referring to the thread starter....Originally posted by kaobeikaobu:if i can edit the first post.... -
u mean this question being asked by ur teacher
in the school wif qn about
students blindfolded >> now know y students r stressed -
heng, i was thinking ways of hacking into mod's accts...Originally posted by huiz:i was referring to the thread starter.... -
-_-"Originally posted by kaobeikaobu:heng, i was thinking ways of hacking into mod's accts... -
Have the question been solved by Fatum? I think dragg has got a more logical approached but I will elaborate it further below:Originally posted by dragg:it still funny. the question indicated a, b and c are all in red hats.
the fact is
c saw a and b in red hats
b saw a and c in red hats
a saw b and c in red hats.
A either saw B or C or both in red hats.
1. Probability of seeing B and C in red hats are 50% each respectively.
B either saw A or C or both in red hats.
1. Probability of seeing A and C in red hats are 50% each respectively.
Hence,
Probability Table
Probability of red hat on,
A - 50%
B - 50%
C - 100%
C saw both A and B in red hats.
1. Confirmation on red hats for both A and B.
2. C will now obeserve A and B and using probability table above as reference.
C walked out because the probability of him wearing red hat is higher.
Q) Why not green on C?
A) Unless A only look at B and B only look at A but the probability that happening is slimmer - Refer to probability table above. Also, do note that it is not possible for only one of them (A or B) to raise his hand.
... okay that will be 1 dollar please. -
Originally posted by TooFree:
they are all wearing red hats. the probability of C wearing a red hat would therefore be the same as A or B.
Have the question been solved by Fatum? I think dragg has got a more logical approached but I will elaborate it further below:
A saw B and C in red hats.
1. Probability of seeing B and C in red hats are 50% each respectively.
B saw A and C in red hats.
1. Probability of seeing A and C in red hats are 50% each respectively.
Hence,
[b]Probability Table
Probability of red hat on,
A - 50%
B - 50%
C - 100%
C saw both A and B in red hats.
1. Confirmation on red hats for both A and B.
2. C will now obeserve A and B and using probability table above as reference. C walked out because the probability of him wearing red hat is higher.
Q) Why not green on C?
A) Unless A only look at B and B only look at A but the probability that happening is slimmer - Refer to probability table above. Also, do note that it is not possible for only one of them (A or B) to raise his hand.
... okay that will be 1 dollar please.
[/b]
C is just smarter...or at least hes made to be. -
Originally posted by JennTS:
Huh?
they are all wearing red hats. the probability of C wearing a red hat would therefore be the same as A or B.
C is just smarter...or at least hes made to be.
As response to your sentence in red. Yes we know that.. but they don't .. -
aiya the three of them standing there like fools for a long time... then C cannot tahan want to go toilet break... then he leave lor...
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hi ppl!
i've posted the right answer in my first post le...it was fun thinking, wasn't it?
alternatively, you can look at the answers of Fatum, hisoka, JennT, DriftingGuy, Advent_Surge, bladez87.
they have all gotten correct answers...hope i didn't leave anyone out!