How fast can you...

Started by zgooh
13/02/2011 16:57
Page 2 of 2
zgooh14/02/2011 18:17

Originally posted by Ggs`
Time to time, I do exercises for keeping my brain in toned. Favorive one is solving a problem.

For example :

The 8 ball problem

This is one of my favorite questions to ask people. Primarily computer science people, as they always get this one wrong :)

Image
The problem is quite simple. You are given 8 identical-looking balls, one of which is heavier than the other 7 (all of which weigh the same). Using an old-fashioned mechanical set of scales you must identify the heavier ball using the scale as few times as possible. The scale is constructed using two bowls and an arm enabling the bowls to either balance or have one bowl rising while the other (and heavier bowl) falling. You can't just add one ball at a time thinking its one weighing, however, you may put any number of balls in each bowl... All you need to solve the puzzle is to use a bit of common sense.

I think I got it.

So, you're gonna put 3ballsx3balls. 2 Things can happen :

1- Bowl R(right) is heavier than bowl L(left)

You will know that the 3balls in the right bowl hide the heavy one.
Therefore, you will take two of them and put them in 2 sepparate bowls.
2 things can happen again :

1-a. One bowl is lighter than the other one and therefore you will know wich one contains the heavy ball.

1-b. They will both be balanced and you will know that the ball you didn't use is the heavy one.

That's the first main case.

2- Both bowls are balanced. 6 balls are not hiding the heavy one.
You therefore end up with 2 balls.
Put them in 2 bowls. BAM ! :D

There you go, how to do it by using the scale twice. Is that it ?

Nubz moviemaker14/02/2011 20:29

never really practised it.. once tried and could made 1 side!

Ggs`14/02/2011 22:56(edited 14/02/2011 23:03)

Originally posted by zgooh
Originally posted by Ggs`
Time to time, I do exercises for keeping my brain in toned. Favorive one is solving a problem.

For example :

The 8 ball problem

This is one of my favorite questions to ask people. Primarily computer science people, as they always get this one wrong :)

Image
The problem is quite simple. You are given 8 identical-looking balls, one of which is heavier than the other 7 (all of which weigh the same). Using an old-fashioned mechanical set of scales you must identify the heavier ball using the scale as few times as possible. The scale is constructed using two bowls and an arm enabling the bowls to either balance or have one bowl rising while the other (and heavier bowl) falling. You can't just add one ball at a time thinking its one weighing, however, you may put any number of balls in each bowl... All you need to solve the puzzle is to use a bit of common sense.

I think I got it.

So, you're gonna put 3ballsx3balls. 2 Things can happen :

1- Bowl R(right) is heavier than bowl L(left)

You will know that the 3balls in the right bowl hide the heavy one.
Therefore, you will take two of them and put them in 2 sepparate bowls.
2 things can happen again :

1-a. One bowl is lighter than the other one and therefore you will know wich one contains the heavy ball.

1-b. They will both be balanced and you will know that the ball you didn't use is the heavy one.

That's the first main case.

2- Both bowls are balanced. 6 balls are not hiding the heavy one.
You therefore end up with 2 balls.
Put them in 2 bowls. BAM ! :D

There you go, how to do it by using the scale twice. Is that it ?

exactly, nice one! :) How much time it took for you?

zgooh15/02/2011 00:00

@Ggs : Around 10 minutes after I came back from school, or maybe a bit more

kafds15/02/2011 04:24(edited 06/03/2011 14:36)

I think my best time was around 2 and a half minutes, but I haven't tried a lot. I'm not patient & smart enough for these mathematical puzzles.

EDIT: 44 seconds! :D

V0ncH...15/02/2011 21:51

fasted was like 50 or 55 sec

Skizo_record holder06/03/2011 13:05

http://www.youtube.com/watch?v=UX8bCAOIAfs

40.95 :/ not the best but atm good :D

BLuex06/03/2011 14:27

Originally posted by Skizo_
http://www.youtube.com/watch?v=UX8bCAOIAfs

40.95 :/ not the best but atm good :D

Cheated!

jack frog06/03/2011 15:17

Originally posted by zgooh
Originally posted by Ggs`
Time to time, I do exercises for keeping my brain in toned. Favorive one is solving a problem.

For example :

The 8 ball problem

This is one of my favorite questions to ask people. Primarily computer science people, as they always get this one wrong :)

Image
The problem is quite simple. You are given 8 identical-looking balls, one of which is heavier than the other 7 (all of which weigh the same). Using an old-fashioned mechanical set of scales you must identify the heavier ball using the scale as few times as possible. The scale is constructed using two bowls and an arm enabling the bowls to either balance or have one bowl rising while the other (and heavier bowl) falling. You can't just add one ball at a time thinking its one weighing, however, you may put any number of balls in each bowl... All you need to solve the puzzle is to use a bit of common sense.

I think I got it.

So, you're gonna put 3ballsx3balls. 2 Things can happen :

1- Bowl R(right) is heavier than bowl L(left)

You will know that the 3balls in the right bowl hide the heavy one.
Therefore, you will take two of them and put them in 2 sepparate bowls.
2 things can happen again :

1-a. One bowl is lighter than the other one and therefore you will know wich one contains the heavy ball.

1-b. They will both be balanced and you will know that the ball you didn't use is the heavy one.

That's the first main case.

2- Both bowls are balanced. 6 balls are not hiding the heavy one.
You therefore end up with 2 balls.
Put them in 2 bowls. BAM ! :D

There you go, how to do it by using the scale twice. Is that it ?

Complicated solution, lol. I'd put 4 Balls in each bowl. Then look wich bowl weights more (let's say Bowl R). Start exchanging one ball at a time (you need max. 4 tries). If suddenly Bowl L weights more, you know wich ball is heavier.

Took me 1 min, lol.





zgooh06/03/2011 19:36

Originally posted by jack frog
Originally posted by zgooh
Originally posted by Ggs`
Time to time, I do exercises for keeping my brain in toned. Favorive one is solving a problem.

For example :

The 8 ball problem

This is one of my favorite questions to ask people. Primarily computer science people, as they always get this one wrong :)

Image
The problem is quite simple. You are given 8 identical-looking balls, one of which is heavier than the other 7 (all of which weigh the same). Using an old-fashioned mechanical set of scales you must identify the heavier ball using the scale as few times as possible. The scale is constructed using two bowls and an arm enabling the bowls to either balance or have one bowl rising while the other (and heavier bowl) falling. You can't just add one ball at a time thinking its one weighing, however, you may put any number of balls in each bowl... All you need to solve the puzzle is to use a bit of common sense.

I think I got it.

So, you're gonna put 3ballsx3balls. 2 Things can happen :

1- Bowl R(right) is heavier than bowl L(left)

You will know that the 3balls in the right bowl hide the heavy one.
Therefore, you will take two of them and put them in 2 sepparate bowls.
2 things can happen again :

1-a. One bowl is lighter than the other one and therefore you will know wich one contains the heavy ball.

1-b. They will both be balanced and you will know that the ball you didn't use is the heavy one.

That's the first main case.

2- Both bowls are balanced. 6 balls are not hiding the heavy one.
You therefore end up with 2 balls.
Put them in 2 bowls. BAM ! :D

There you go, how to do it by using the scale twice. Is that it ?

Complicated solution, lol. I'd put 4 Balls in each bowl. Then look wich bowl weights more (let's say Bowl R). Start exchanging one ball at a time (you need max. 4 tries). If suddenly Bowl L weights more, you know wich ball is heavier.

Took me 1 min, lol.

You can't use it many times. 2 is the minimum

Skizo_record holder06/03/2011 21:09

http://www.youtube.com/watch?v=J2Q2ZpUfapk

jack frog06/03/2011 21:33

Originally posted by zgooh
Originally posted by jack frog
Originally posted by zgooh
Originally posted by Ggs`
Time to time, I do exercises for keeping my brain in toned. Favorive one is solving a problem.

For example :

The 8 ball problem

This is one of my favorite questions to ask people. Primarily computer science people, as they always get this one wrong :)

Image
The problem is quite simple. You are given 8 identical-looking balls, one of which is heavier than the other 7 (all of which weigh the same). Using an old-fashioned mechanical set of scales you must identify the heavier ball using the scale as few times as possible. The scale is constructed using two bowls and an arm enabling the bowls to either balance or have one bowl rising while the other (and heavier bowl) falling. You can't just add one ball at a time thinking its one weighing, however, you may put any number of balls in each bowl... All you need to solve the puzzle is to use a bit of common sense.

I think I got it.

So, you're gonna put 3ballsx3balls. 2 Things can happen :

1- Bowl R(right) is heavier than bowl L(left)

You will know that the 3balls in the right bowl hide the heavy one.
Therefore, you will take two of them and put them in 2 sepparate bowls.
2 things can happen again :

1-a. One bowl is lighter than the other one and therefore you will know wich one contains the heavy ball.

1-b. They will both be balanced and you will know that the ball you didn't use is the heavy one.

That's the first main case.

2- Both bowls are balanced. 6 balls are not hiding the heavy one.
You therefore end up with 2 balls.
Put them in 2 bowls. BAM ! :D

There you go, how to do it by using the scale twice. Is that it ?

Complicated solution, lol. I'd put 4 Balls in each bowl. Then look wich bowl weights more (let's say Bowl R). Start exchanging one ball at a time (you need max. 4 tries). If suddenly Bowl L weights more, you know wich ball is heavier.

Took me 1 min, lol.

You can't use it many times. 2 is the minimum


He didn't write that. And maybe you take the right ball on second try :)

InfinityBG07/03/2011 01:31

Originally posted by Skizo_
http://www.youtube.com/watch?v=UX8bCAOIAfs

40.95 :/ not the best but atm good :D

can't get it.

V0ncH...08/03/2011 01:14

Originally posted by Skizo_
http://www.youtube.com/watch?v=UX8bCAOIAfs

40.95 :/ not the best but atm good :D

naice one
but how u get it soo smooth movements,
petroleum jelly?

DiDo-Grecord holder08/03/2011 13:07

Originally posted by Nukk
i cant do it :DD

me too lol

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