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Megamickel
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Megamickel
902 posts
Peasant

Something we worked on today in class, I thought I'd share it. THINK THIS THROUGH. There is a solution. I have more to follow.

Three college students are selected to be on the hit TV game show, Dot of Fortune. One of these students has been enlightened to the ways of mathematics, and the other two are sociology majors. on this game show, there are no mirrors, no reflective surfaces, etc. - there is no way to cheat. When the students go on the game show, they are blindfolded and a dot is placed on each one of their foreheads. The blindfolds are removed and they are told that if they see a red dot, they are to raise their hands. In this case, they all have red dots on their heads, so they all raise their hands (they can't see their own dot). Whoever figures out which color dot they have first wins. After a few minutes, one of the students looks up and says "I have a red dot on my forehead." How did he come to this conclusion?


Note: He did not simply guess or speculate, he was absolutely certain he had a red dot. He had not seen his own forehead.
  • 31 Replies
necromancer
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necromancer
750 posts
Peasant

The archaeologist measures three stones against another three. She either takes the heaviest set of three or if they are of equal weight the three left out. She then wishes for a second balance and weighs one of those three against another one of the three. She either takes the heavier one, if both are of equal weight she takes the stone that was set aside. Then she leaves as the wealthiest, most powerful person ever.

Alternate: The archaeologist realizes money and power aren't everything and uses the final wish for a happy life, world peace, food for the hungry, etc. Then she takes one of the jewels at random to sell.

Alternate: The genie said one of the jewels is heavier but never said that was necessarily the Jewel of Medina. The archaeologist takes the heavier jewel but doesn't have infinite wealth/power.

Megamickel
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Megamickel
902 posts
Peasant

Good answers, guys.

Now, same question, only this time, all you know is that the Jewel of Medina is a different weight - you don't know if it's heavier or lighter.

Go.

Megamickel
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Megamickel
902 posts
Peasant

You'll have to alter your method a little bit for this one.

necromancer
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necromancer
750 posts
Peasant

I can't think of how you could do this with two scales, with three definitely, but with two and you can't decide which of the three sets of three to take after the first weighing, unless the two sets you weigh are of identical weight... Hmmm...

woody_7007
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woody_7007
2,662 posts
Peasant

i have heard of a puzzle which has 12 stones and one heavier and one lighter which gives you 3 weighs but i dont know about this one. hmm.

Ricador
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Ricador
3,722 posts
Shepherd

I think that you have to have three balances. I thought about it for a while and i just can't get it without three balances.

woody_7007
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woody_7007
2,662 posts
Peasant

I agree i can think of no way of doing it without 3 balances. However the answer is probably impossibly ingenious.

Ricador
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Ricador
3,722 posts
Shepherd

is probably impossibly ingenious.


Which is exactly the reason i am going to ask:

CAN YOU TELL US. PLEASE PLEASE PLEASE PLEASE PLEASE.
woody_7007
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woody_7007
2,662 posts
Peasant

No he probably wont. He will let us stew for a few days i bet.

Drace
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Drace
3,880 posts
Nomad

Someone told him he had a red dot :P

Ok seriously,


After a few minutes, one of the students looks up and says "I have a red dot on my forehead." How did he come to this conclusion?


Looks up o.O?
MosaicMan3
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MosaicMan3
78 posts
Constable

Simple... I think

Put the stones in groups of 3. Weigh them. If their both exact put 2 of the 3rd group on one side, and a stone that you know is the correct weight of the other.

the side........ nvm my way of thinking would need a 3rd scale... your all corret in my book

Ricador
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Ricador
3,722 posts
Shepherd

He will let us stew for a few days i bet.


Yes you are probably right, because as you can see he is not posting.

Since none of us can seem to figure it out, i guess we will just have to wait.

:P
Strop
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Strop
10,816 posts
Bard

Sorry guys, wrong forum. This really does go in the tavern

99percentcomplete
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99percentcomplete
390 posts
Nomad

It depends how much heavier or lighter the real jewel is. If it is noticeable enough you could just weight it with your hands.

MosaicMan3
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MosaicMan3
78 posts
Constable

it's just a slight differance, and you would need a scale.

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