Dave's ESL Cafe's Student Discussion Forums

[ad-miral]

thanks for the graphical explanation of the new vocabulary

I have six balls, two are silver, two are gold, and two are copper.
I take one silver ball, one gold ball and one copper ball and put them aside. Now I have two groups. Every group consists of a gold, a copper, and a silver ball.

Then I weigh both groups. One group must be heavier than the other. But there could be two possibilities: (The colour is unimportant now, because both groups have the same colour combination) (I will say L to the light balls and H to the heavy balls)

First weigh:
1. possibility 2.possibility
LLL | HHH ......... LHL | HLH

One side must be heavier than the other one. In 1st possibility we will have our result. But because there is also the 2nd possibility, we have to weigh the second time. The second weigh will be used with the heavier 3 balls. Two balls at one side, one at the other. (Means we either weigh HHH or HLH)

Second weigh:
1. possibility
HH | H
In this case, the left two balls will be exactly twice as heavy as the right ball. So we can say they are the 3 heavy balls and the other three must be the 3 light balls. And we can say for sure that it's the 1st possibility.
Let's say HH / 2 = H

So we will have the three heavy balls.

2. possibility
HH | L
In this case, the left balls will be heavier than twice the right ball. So we can say HH / 2 > L

That means we have two of the heavy balls. We substitute the right ball with the one of the missing colour and we will have the same result as the 1. possibility.

3. possibility
HL | H
In this case, the left balls will be lighter than twice the right ball. So we can say HL / 2 < H

Here the black sheep is on the left side... Don't we need three weighs to say it exactly?
_________________
If I say "I love you" to someone, then I also have to say "I also love everyone else inside you, I love the whole world because of you, I also love myself inside you." -- Erich Fromm, the Art of Love

[beancurdturtle]

This puzzle was first told to me by my friend from Moscow Russia. He is a very smart guy, and he speaks 5 languages fluently.

He gave the puzzle to me and 3 other software and network engineers where we worked together. The shortest time to solve it was two days.

It took me the longest (3 weeks) because I have the least interest in puzzles like this.

The puzzle is difficult to explain - the answer more difficult. My Russian friend explained with drawings. I can't draw here - so here's a link on the internet with the solution:
http://www.cut-the-knot.org/blue/6Balls2Weighings.shtml#solution
_________________
Daniel

�Be who you are and say what you feel because those who mind don't matter and those who matter don't mind.�
--Dr. Seuss

[ad-miral]

Gosh! Why making so difficult puzzles??? The aim is that we guess the answer to have fun and not that we think about it day and night, and at the end we got to know that we were wrong.

Please do it without a calculator:

Take 1000
plus 40
again plus 1000
plus 30
again plus 1000
plus 20
plus 1000
and plus 10

What's the answer? If you say it's 5000, then you are wrong
_________________
If I say "I love you" to someone, then I also have to say "I also love everyone else inside you, I love the whole world because of you, I also love myself inside you." -- Erich Fromm, the Art of Love

[hoshi]

4100 I received that game by mail long time ago
_________________
God gave us two ears to hear, two eyes to see and two hands to hold. But why did God gave us only one heart? Because He wants us to find the other one!

[ad-miral]

[hoshi]

Do you want me to start another one? well I will think about it. Maybe I'll be posting it tomorrow...
_________________
God gave us two ears to hear, two eyes to see and two hands to hold. But why did God gave us only one heart? Because He wants us to find the other one!

[hoshi]

Hey after all I found one

The mayor told the people that he will give an opportunity to a prissioner to be free. This was because he wanted to celebrate his 25 years as the mayor. But the mayor tells everybody that there is a test the prissioner had to pass. The test was very simple. The mayor would give him a box. The box had 10 balls, 9 black balls and a white ball. The mayor would ask him to take a random ball from the box and if he could take out the white one he would be free.

Few hours passed and the prissioner discovered that all the balls inside the box would be black because the mayor told the secret to an employee.

The next day the mayor asked the prissioner infront of all the town to take out a ball. I repeat, If he could take out the white one he would be free. He played the game and he was free but how if all the balls were black?
_________________
God gave us two ears to hear, two eyes to see and two hands to hold. But why did God gave us only one heart? Because He wants us to find the other one!