brainbreaker

gazzy · Post by **gazzy** » Sat May 28, 2005 10:40 am

i was looking for some puzzles on the internet, i had nothing to do.
then i stumbled on this

can anyone solve this?

http://www.ongein.com/ongein/item.aspx?ID=1115

pontiac · Post by **pontiac** » Sat May 28, 2005 11:39 am

That one is quite old and easy to solve if you use a ruler and not a math book

Pontiac

gazzy · Post by **gazzy** » Sat May 28, 2005 1:42 pm

*holds ruler against screen, sees where the hole comes from and applies head to hard surface*

pontiac · Post by **pontiac** » Sat May 28, 2005 2:40 pm

gazzy wrote:*holds ruler against screen, sees where the hole comes from and applies head to hard surface*

You did apply a ruler physically on your computer screen? If it's a CRT (one with a curved surface) you are banging the head not hard enough.

The puzzle makes it rather hard being solved, because it just hides obvious facts quite clevery behind the human mind/senses.
I solved it all by myself (the mathematical way, no ruler involved .. the numbers just don't add up), but before this i thought 2 days straight into the wrong direction, misleaded by the friend who gave it to me

Pontiac

pontiac · Post by **pontiac** » Sat May 28, 2005 3:01 pm

Acutally i have a cool counter-riddle here:

"Show a way to slice ANY angle between 0 and 360Â° into three smaller equal angles (speak: create an angle one third as big as the original)....
....But using only a pen, a ruler and a pair of compasses."

Happy riddling

Pontiac

gazzy · Post by **gazzy** » Tue May 31, 2005 5:59 pm

i have a flatscreen, so my head is ok

and with your riddle, im am horribble with angles at maths, so
thats the first reason that i couldn't solve the puzzle

the rest of my maths doesn't suck that hard(i am only for the first year on high school)

pontiac · Post by **pontiac** » Wed Jun 01, 2005 12:11 am

gazzy wrote:i have a flatscreen, so my head is ok

Good to hear

and with your riddle, im am horribble with angles at maths, so
thats the first reason that i couldn't solve the puzzle

Ok, i was unfair when posting the last riddlle. the answer is hidden somewhere in THIS post,. you just have to search

Pontiac

Halleck · Post by **Halleck** » Wed Jun 01, 2005 8:17 am

Um... I can do bisection!

EDIT: Ahh... tricky tricky.

Post by **chuck_starchaser** » Thu Jun 02, 2005 2:24 pm

Does the solution require full precision in finite time?

If one can bi-sect, one can go another step and divide the angle into quarters.
Then I'd move-in one quarter from each side and bisect the middle quarters into 1/16th's. Then move in one sixteenth form each side, and divide what remains into 64th's, and so on...
1/4 + 1/16 + 1/64 + 1/256 + ... = 1/3

The first puzzle reminds me a bit of the old one about the three guys that go to a pub and order 3 beers. When the waitress comes she forgets it was happy hour and charges them $15. Each pulls out a $5 bill and give her the three bills. When she takes their payment to the cash, the casheer says "Don't you know? It's 3 beers for the price of two, at this time." So she rushes to give the guys $5 back, but, along the way she thinks "well, they split the bill, but how are they going to split $5?", so she decides to tell them that the bill was $12, gives them back $3, which they dutifully split 3-ways.
Now the question is: Each spent only $4, in the end. $4 x 3 = $12. There's $2 in the waitress' pocket. So that makes it $14. Where's the missing dollar?

pontiac · Post by **pontiac** » Thu Jun 02, 2005 4:58 pm

chuck_starchaser wrote:Does the solution require full precision in finite time?

I will meet you in the middle here. If you find a way to 'survive' the infinite time to finish it and then tell it to me ... then yes

But i think normally these 'ruler and pair of compasses' riddles need to be solved in finite time .

The first puzzle reminds me a bit of the old one about the three guys that go to a pub and order 3 beers. When the waitress comes she forgets it was happy hour and charges them $15. Each pulls out a $5 bill and give her the three bills. When she takes their payment to the cash, the casheer says "Don't you know? It's 3 beers for the price of two, at this time." So she rushes to give the guys $5 back, but, along the way she thinks "well, they split the bill, but how are they going to split $5?", so she decides to tell them that the bill was $12, gives them back $3, which they dutifully split 3-ways.
Now the question is: Each spent only $4, in the end. $4 x 3 = $12. There's $2 in the waitress' pocket. So that makes it $14. Where's the missing dollar?

I have heard this riddle in at least a few hundred variations (with the only differenc that it's normally 30 instead of 15 'things') ...
... and if you try to calculate as the riddle-teller want you to, you will never get the solution

The last dollar got lost in 'bad math'.

Pontiac

PS: For german readers: Google groups: de.rec.denksport especially the FAQ

There is an english equivalent for sure... but i do not know the name.