Brain Teaser

JoannaK

JoannaK

I heard this on the radio last night, and wondered if any one can figure it out. I don't know the answer, and I haven't tried to figure it out yet....

3 guys order pizza, and the total cost is $30

the delivery guy delivers the pizza and takes a $10 note from each of the guys.

On the way home the delivery guy realises that he's over charged the guys by $5. He thinks...well, I deserve a tip, so I'll keep $2 for myself, and give the guys back $1 each....so effectively the guys paid $9 each for the pizza...

Now, $9 each by 3 guys is $27 and the pizza guy keeps $2, so where has the other $1 gone?
 
Answer: The trick is to go back to the beginning. There is no real problem here. They only paid $27. Don't be fooled by the question of where the other dollar is... it is there... look at the problem from this point of view... They each paid $9 so they paid a total of $27. $25 went for the pizza and $2 for the tip... done. end of story. The rest is just subterfuge.

There you go Joanna! Amazing what you can find on google in a couple of seconds :)
Now you can relax for the day.... ;)
 
Here is an old and probably simple but a good one...

An spaceman is lost in a vast spaceship with no air.

He knows there is only one way out. He only has so much oxygen left. He only has enought to get the exit directly and escape to his ship.

He follows the corridoor until it comes to two doors.

He sees two computers with READ ME on computer one.

He presses the button on computer one and the computer says "after reading this you may type a question to either this computer one or the other computer two.

In answer to that question One of the computers is programmed to lie and One is programmed to tell the truth.

You can then select the door and pass through but you cannot pass back and if you have chosen the wrong door you are trapped and will die from lack of oxygen"

How does he get the answer to which is the correct door?:confused:

Peter 14.7
 
Peter that's a modern twist on an oldie (it's even in the movie Labyrinth).

He types:
"If I asked the other computer, which door would he indicate leads to the exit?"

He should then take the door opposite to what's indicated!
Regardless of which computer is asked, it will indicate the wrong door.


How about this one (related to finance so appropriate to Somersoft):

You have twelve coins, eleven identical and one different. You do not know whether the "odd" coin is lighter or heavier than the others. Someone gives you a balance and three chances to use it.

The question is: How can you make just three weighings on the balance and find out not only which coin is the "odd" coin, but also whether it's heavier or lighter?

Cheers,

Aceyducey
 
Aceyducey said:
Peter that's a modern twist on an oldie (it's even in the movie Labyrinth).

He types:
"If I asked the other computer, which door would he indicate leads to the exit?"

He should then take the door opposite to what's indicated!
Regardless of which computer is asked, it will indicate the wrong door.


How about this one (related to finance so appropriate to Somersoft):

You have twelve coins, eleven identical and one different. You do not know whether the "odd" coin is lighter or heavier than the others. Someone gives you a balance and three chances to use it.

The question is: How can you make just three weighings on the balance and find out not only which coin is the "odd" coin, but also whether it's heavier or lighter?

Cheers,

Aceyducey
Click to expand...

I am positive we nutted this one out a year or two ago in the forum.

I reckon I could work it out but as I have seen it before it wouldn't be fair. it is quite complex to write down but easy enough to visualise.
 
Aceyducey said:
Peter that's a modern twist on an oldie (it's even in the movie Labyrinth).

Cheers

Aceyducey
Click to expand...

I am absolutely not suprised you answered this Acey.

I saw the puzzle as a kid on a Doctor Who episode with mummys ( egypt) so I knew being an ex Sci Fi Geek you would know the answer.:D

Peter 14.7
 
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