Another logic problem

[Amail]

The Monty Hall thread got me thinking of another logic problem I think is pretty fun. I suspect it has been posted before, but I can't find it with Search.

So...

Three guys on the road stop at a cheap hotel for the night. The sign says $30/night. The guys are down to the last of their money, so they decide to share one room, each paying $10.

After they've paid their $30 and head up to their room, the manager realizes he's made a mistake. It's Friday, and the room is only $25 on Fridays. He sends the bellboy up to their room with their $5 reimbursement.

The bellboy hands them the $5, but of course they can't split it evenly, so they all take back $1 and give the bellboy a $2 tip. Pretty cool, they each save a dollar and they get to tip the bellboy!

After a while one of them, thinking there's a problem says "Wait a minute, we each paid $9, which is $27, and we paid the bellboy $2. That's $29. What happened to the other dollar?"

So, what did happen to the other dollar?

[jriera]

Nothing happened to the dollar. All the money is still there. Yes, they each ended up paying $9 each for a total of $27. Plus the $3 they got back is a total of $30-it's all there. They were supposed to pay $25 but they paid $27, which makes sense because the bellhop kept $2.

Charges: $25 for the room + $2 for the bellhop=$27 $30 initial charge - $3 refund = $27 Each paid $9 and $9 x 3 = $27

The trick is in the statement, "The three men had now paid $9 each, or a total of $27. This plus the $2 the bellhop kept for himself makes a total of $29."

The $27 is the total payment and $2 is a cost, not a payment! It just happens to add up to $29 giving the illusion of a missing dollar.

[Aerkuld]

Even I'm not going to argue this...

[Amail]

Originally posted by jriera
Nothing happened to the dollar. All the money is still there. Yes, they each ended up paying $9 each for a total of $27. Plus the $3 they got back is a total of $30-it's all there. They were supposed to pay $25 but they paid $27, which makes sense because the bellhop kept $2.

Charges: $25 for the room + $2 for the bellhop=$27 $30 initial charge - $3 refund = $27 Each paid $9 and $9 x 3 = $27

The trick is in the statement, "The three men had now paid $9 each, or a total of $27. This plus the $2 the bellhop kept for himself makes a total of $29."

The $27 is the total payment and $2 is a cost, not a payment! It just happens to add up to $29 giving the illusion of a missing dollar.

Oh, fine, go ahead and ruin the fun in the second post!

[klaucke]

Here is a commonplace logic problem or paradox:

Suppose there is an island where all the men are clean shaven. They either shave themselves, or they go to the barber (no exceptions). Therefore, the barber shaves all men who do not shave themselves. Does the barber shave his own face?

[Amail]

There are two barbers, and each shaves the other.

N'est ce pas?

[klaucke]

No, there is a single barber who shaves all men who do not shave themselves.

[Aerkuld]

The barber shaves the barber.

[lendaddy]

Originally posted by klaucke
Here is a commonplace logic problem or paradox:

Suppose there is an island where all the men are clean shaven. They either shave themselves, or they go to the barber (no exceptions). Therefore, the barber shaves all men who do not shave themselves. Does the barber shave his own face?

The barber is a woman

But seriously, why couldn't the barber shave himself assuming it was a he?

[Steve Carlton]

Does she shave herself?

[mattdavis11]

No, she saves herself from being shaved.

[klaucke]

Originally posted by lendaddy
The barber is a woman

But seriously, why couldn't the barber shave himself assuming it was a he?

I suppose I wasn't clear, the island is only composed of men. There are no women. If the barber shaves himself, then he will be a man who shaves himself, and the barber only shaves men who do not shave themselves. So he can't shave himself. But then the barber (himself) should shave him because he does not shave himself... etc.

[Clay Perrine]

Ok.. here's mine..


There is a room with a one way door. Inside the room are 3 light bulbs. Outside the room are three light switches. You cannot see the lights by holding the door open, you must enter the room to see them.

How do you tell which switch is hooked to each bulb?

[nostatic]

look through the window while you flick the switches

or view the nanny cam

of go to the bar...who the hell cares about which switch turns on which light?

[Aerkuld]

Originally posted by Clay Perrine
Ok.. here's mine..


There is a room with a one way door. Inside the room are 3 light bulbs. Outside the room are three light switches. You cannot see the lights by holding the door open, you must enter the room to see them.

How do you tell which switch is hooked to each bulb?

Find the wiring diagram.

[dad911]

turn switch 1 on for a minute, turn it off.
turn switch 2 on
go in room
bulb 1 is warm, but off
bulb 2 is on
bulb 3 is off

[klaucke]

Easy, you turn one light on, leave it on for 10 min, then turn it off. Turn another light on and go inside. You know which switch works the light that is on (you left it on), and you can find the bulb which is warm out of the two that are off, so you know which bulb was on for 10 minutes prior. This of course assumes incandescent bulbs, although I suppose it would work to a lesser degree w/ halogens.

[ikarcuaso]

...the chicken or the egg?

Discuss.

[Aerkuld]

Originally posted by klaucke
Easy, you turn one light on, leave it on for 10 min, then turn it off. Turn another light on and go inside. You know which switch works the light that is on (you left it on), and you can find the bulb which is warm out of the two that are off, so you know which bulb was on for 10 minutes prior. This of course assumes incandescent bulbs, although I suppose it would work to a lesser degree w/ halogens.

And now you're in a room with one lit lightbulb and you can't open the door. I'm leaving the switches alone and off to join nostatic in the bar, he's already on his second beer.

[nostatic]

dude, what took you?!? Your beer is warm...