Puzzle Me This:

Mike(VA) · 07-14-2009, 06:14 AM

Old puzzle, but fun just the same. Can keep you busy for a while.

If I give you 10 pennies and 9 of them weight exactly the same and 1 weighs more or less than the others, can you tell me how to find out which one weighs more or less than the others using just a balance scale and three tries?

HINT: You can't easily describe the solution without drawing it out.

Any more mind twister puzzlers out there? The "Who owns the zebra one comes to mind."

**shanekw1** · 07-14-2009, 11:00 AM

Divide them into 2 piles of 5 pennies, weigh them and find the heavier pile (if your looking for a heavier penny, lighter pile for a lighter penny).

Take the pile you identified as heavier and split it into 2 piles of 2 and you will have one left over, weigh the 2 piles.

If they are balanced, the one left over is the heavier penny, otherwise find the heavier pile again and weigh the 2 pennies to find the heavier one.

SelfContract · 07-14-2009, 11:14 AM

Quote:

Originally Posted by shanekw1

Divide them into 2 piles of 5 pennies, weigh them and find the heavier pile (if your looking for a heavier penny, lighter pile for a lighter penny).

Take the pile you identified as heavier and split it into 2 piles of 2 and you will have one left over, weigh the 2 piles.

If they are balanced, the one left over is the heavier penny, otherwise find the heavier pile again and weigh the 2 pennies to find the heavier one.

-------------------------------

Your answer is only good for if you know ahead that culprit penny is heavier or lighter (first before scale)? Let 10 pennies = 9a + x, where x = culprit penny (heavier or lighter), then divide-and conquer mathematical method to solve it in 3 steps down..

However, if you can NOT know beforehand it is lighter or heavier, can it be done in 3 steps and come up with a (discover) conclusion => A single penny of Lighter or Heavier (after 3 steps) ??

Hmm... a tricky question indeed!!!.. I give up!

Mike(VA) · 07-14-2009, 03:06 PM

You do not know whether the odd penny is heavier or lighter so dividing them into two piles tells you nothing. On the scale, is the side down the heavier one or the side up the lighter one?

Hint: Flow charts work.

Mike(VA) · 07-14-2009, 03:39 PM

Ok, selfcontract, try this one:

Solve this using the following 15 clues:

1. There are five houses in a row, each of a different color and
inhabited by people of different nationalities, with different
pets, drinks, and flowers.
2. The English person lives in the red house.
3. The Spaniard owns the dog.
4. Coffee is drunk in the green house.
5. The Ukrainian drinks tea.
6. The green house is immediately to the right (your right) of the
ivory house.
7. The geranium grower owns snails.
8. Roses are in front of the yellow house.
9. Milk is drunk in the middle house.
10. The Norwegian lives in the first house on the left.
11. The person who grows marigolds lives in the house next to the
person with the fox.
12. Roses are grown at the house next to the house where the horse is
kept.
13. The person who grows lilies drinks orange juice.
14. The Japanese person grows gardenias.
15. The Norwegian lives next to the blue house.

So given the 15 clues, who drinks water? And who owns the zebra?

maninthesea · 07-14-2009, 05:27 PM

dont have time to work out all the details but the first step woudl be weigh 2 piles of 3. if they are the same then your bad penny is in the 4 you did not weigh. If they do not ballance then the bad penny is one of the 6 you did weigh.

Mike(VA) · 07-14-2009, 05:38 PM

maninthesea is getting close. When you find the time, its challenging.

maninthesea · 07-15-2009, 07:30 AM

OK if 3 + 3 ballance then there are 4 left containing a bad penny.

Put 1 + 1 on the scale. If they dont balance then bad penny is on the scales. Take lighter one off and replace with any one of the good pennies.

If they balance then the one you took off was light. If the heavy penny is heavy again then its the bad heavy penny.

If the 1 + 1 do ballance in the second weighing then bad penny is one of the other two.

Swap one penny in. If un balanced then it is bad penny and it will show if it is light or heavy.

If scales ballance then the remaining penny is bad and I have no Idea how to tell if its light or heavy without swapping it in.

maninthesea · 07-15-2009, 07:49 AM

If 3 + 3 from step one dont ballance then other four are good bad penny is on hte scale.

Pull the three from the heavy side and swap on of the light ones to the other side and add one good penny.

If light side stays light then bad penny is there. and is light. pull one of those off and put good penny on other side. if still light then light penny is on the scale. if ballanced then the one you pulled was light.

If scales ballance from step 2 then one of the three you pulled from the heavy side is heavy. try to ballance two of those. If not ballanced then heavy one is bad penny & Heavy. If they do ballance then the one you did not put on the scale is bad and heavy.

Mike(VA) · 07-15-2009, 08:34 AM

Hmmm.... you are not covering all possibilities.

Pull the three from the heavy side and swap on of the light ones to the other side and add one good penny.

At this point, you don't know if the bad penny is heavier or lighter and won't be able to tell which one and its difference.

maninthesea · 07-15-2009, 11:12 AM

Quote:

Originally Posted by Mike(VA)

Hmmm.... you are not covering all possibilities.

Pull the three from the heavy side and swap on of the light ones to the other side and add one good penny.

At this point, you don't know if the bad penny is heavier or lighter and won't be able to tell which one and its difference.

Umm Yea I know that I had a group of three pennies that were lighter than the groop of three I took off. So either one of those three is light or one of the other three are heavy. so............ if I move one of the suspected light pennies over and add one pennie that I now is good(from the 4 that have not been on the scale yet. I have three posibilities.
1. the scales ballance and that means all the penies on the scale are good which means the three pennies I took of the scale in the first step contain a heavy pennie. 2. the two pennies from the original stack of 3 light pennies end up lighter than the one good penny plus the one I moved over. Then the light pennie is still in that stack of two. so one of thos goes on the scale with a good pennie if it ballances then the other is light. if it does not then the lightest pennie on the scale is the bad light pennie.
3. the side that got one pennie moved to and one good penny put on it is light. Then of course the pennie that got moved is light.

ChainsawCharlie · 07-15-2009, 02:10 PM

...

edited for clarity

ChainsawCharlie · 07-15-2009, 02:18 PM

edited for clarity

ChainsawCharlie · 07-15-2009, 02:35 PM

Divide into three stacks.

Step 1. Weigh two stacks. If they balance,
Step 2. Swap one of the stacks out. If they still balance
Step 3. Penny left out is the culprit. Weigh it against another penny. This will tell you if it is heavier or lighter.

Now...If the first two balance in Step one

Step 2. Swap one of the stacks out. If the scale tilts down, you know you have a heavy penny in this stack. If it tilts up, you know you have a light penny.

Take this stack, split into three pennies.

Step 3, Weigh two pennies. The scale will either tilt, telling you which penny is heavy or ligh, or it will balance, showing that the penny left out from this group is heavy or light.

Finally-

If the the first two stacks do not balance from the start (Step 1),

Step 2. replace one stack. If you remove the heavy stack, and the scale remains out of balance, you will know you have a light penny in the side you did not remove. If the scale balances, you know you have a heavy penny in the stack you removed.

Likewise, if you replace the light stack, and the scale reamins unbalanced, you know you have a heavy penny in the stack not swapped. If the scale comes into balance, you know you have a light penny in the stack you removed.

Repeat step 3.,

ChainsawCharlie · 07-15-2009, 03:04 PM

Quote:

Originally Posted by Mike(VA)

]

So given the 15 clues, who drinks water? And who owns the zebra?

the Norwegian drinks water and the Jap has the zebra

Mike(VA) · 07-15-2009, 03:56 PM

Charlie said:

Step 3, Weigh two pennies. The scale will either tilt, telling you which penny is heavy or light,
This won't tell you which is the different penny. One could be heavy or the other one light.

or it will balance, showing that the penny left out from this group is heavy or light.

Good try, but if it balances at this point, that was your third try and it will take one more try to tell if the left over penny is lighter or heavier than the other 9.

ChainsawCharlie · 07-15-2009, 04:17 PM

Quote:

Originally Posted by Mike(VA)

Charlie said:

Step 3, Weigh two pennies. The scale will either tilt, telling you which penny is heavy or light,
This won't tell you which is the different penny. One could be heavy or the other one light.

[/quote]

In both instances, you will know after step two if you are dealing with a light or heavy penny.

Step 1. Place one stack of three on the right side of the scale, and one on the left. If they balance,

Step 2. replace the right side stack with the unweighed stack. Since the left side stack weighs the same as the one you just removed, you will know that if the right side drops, is a heavy penny in it. If the right side rises, you will know it has a light penny in it.

Quote:

or it will balance, showing that the penny left out from this group is heavy or light.

Good try, but if it balances at this point, that was your third try and it will take one more try to tell if the left over penny is lighter or heavier than the other 9.

that will already have been determined.

ChainsawCharlie · 07-15-2009, 04:22 PM

If the first two are off balance in step 1

Step 2. If the right side stack is heavy and you replace it, one of two things will happen-the scale will still show heavy on the right, telling you both stacks you weighed on the right are the same, and that the left side has a light penny, or

The scale will balance, telling you the newly added stack is the same as the left stack, which tells you the stack you removed from the right has a heavy penny.

Got it? When you get to step three, you will already know what you are dealing with-light or heavy.

Mike(VA) · 07-15-2009, 04:31 PM

ok, I misread:

Now...If the first two balance in Step one

It was a matter of wordsmithing that I missed.

My Dad gave me that puzzle when I was in the 9th grade and it took me about 4 weeks to figure it out. Drew out scales and options and everything. Guy never gave me any hints at all. He had others but I forgot them except the zebra one. He used to be a P-2 pilot doing coastal patrol and they passed their time doing these. Even today, I don't have the answer to hand out unless I solve it all over again.

Don't know if you can find the answer on the net to this one but the zebra one is easy. Still took me a while when I was young. (No internet, then)

ChainsawCharlie · 07-15-2009, 04:58 PM

Scenario 1:

split pennies into three stacks, set one aside.

Step 1.Stack 1 on the left, stack 2 on the right. If they balance,
Step 2. replace stack 2 with stack 3. If they still balance, all 9 pennies in 1,2 and 3 weigh the same.
Step 3. weigh one of these pennies against penny 10. You will know whether it is lighter or heavier.

----------------------------------------------------------------------------------

Scenario 2.

split pennies into three stacks, set one aside.

Step 1. Stack 1 on the left, stack 2 on the right. if they balance
Step 2. Replace stack 2 with stack 3.

A. If the right side of the scale drops (stack 3) you will know stack three has a heavy penny.

Split stack 3 into three individual pennies.

Step 3. 1 on the left, 2 on the right, 3 set aside.
If they balance, that tells you penny 3 heavy. If they do not balance, you will know which is the heavy penny.

B. If the right side of the scale rises (stack 3), you will know stack three has a light penny.

Step 3. 1 on the left, 2 on the right, 3 set aside.
If they balance, that tells you penny 3 light. If they do not balance, you will know which is the light penny.

--------------------------------------------------------------------

Scenario 3a:

split pennies into three stacks, set one aside.

Step 1. Stack 1 on the left, stack 2 on the right.
Stack three will weigh the same as either Stack 1 or stack 2.

Step 2. If stack two is heavy, Replace stack 2 with stack 3. If the right side remains heavy, then you know stack two and stack three weigh the same, therefor stack 1 has a light penny.

-----------------------------------------------------------------------------------
Scenario 3b

Step 1. Stack 1 on the left, stack 2 on the right.
Stack three will weigh the same as either Stack 1 or stack 2.

Step 2. If stack two is light, Replace stack 2 with stack 3. If the right side remains light, then you know stack two and stack three weigh the same, therefor stack 1 has a heavy penny.

Step 3. 1 on the left, 2 on the right, 3 set aside.
If they balance, that tells you penny 3 is the heavy penny.

Sc. 2 and 3, you will have determined through process of elimination that the tenth penny (set aside) weighs the same as the two stacks of three that were equal in weight, and it doesn't need to be weighed.

Maybe there is more than one solution to this puzzle? The method I listed above will give you the results in three steps, and you WILL KNOW-light or heavy.

07-14-2009, 06:14 AM	#1
Mike(VA) View Profile Mike(VA) Custom Stuff Send Message Follow Blogs (0) Threads (859) Photos (0) Reviews (0) Projects (0) Toolbox (0) View All Activity Custom Stuff Trade: General Contractor - Custom Renovations Join Date: Jan 2008 Location: Manassas, VA Posts: 859	Puzzle Me This: Old puzzle, but fun just the same. Can keep you busy for a while. If I give you 10 pennies and 9 of them weight exactly the same and 1 weighs more or less than the others, can you tell me how to find out which one weighs more or less than the others using just a balance scale and three tries? HINT: You can't easily describe the solution without drawing it out. Any more mind twister puzzlers out there? The "Who owns the zebra one comes to mind." __________________ __________________________________________________ ___________ I EXPECT THAT SOMEDAY I WILL SEE THE FRUITS OF MY LABOR. IS IT SOMEDAY YET? Clifton, Great Falls, McLean, Fairfax Station, Manassas, Virginia Renovation Contractor

07-14-2009, 11:00 AM	#2
shanekw1 View Profile shanekw1 Trailer park boy Send Message Follow Blogs (0) Threads (3,604) Photos (0) Reviews (2) Projects (0) Toolbox (2) View All Activity Trailer park boy Trade: Remodeling Join Date: Mar 2008 Location: Castlegar, BC, Canada Posts: 3,604	Re: Puzzle Me This: Divide them into 2 piles of 5 pennies, weigh them and find the heavier pile (if your looking for a heavier penny, lighter pile for a lighter penny). Take the pile you identified as heavier and split it into 2 piles of 2 and you will have one left over, weigh the 2 piles. If they are balanced, the one left over is the heavier penny, otherwise find the heavier pile again and weigh the 2 pennies to find the heavier one. __________________ "Industry without art is brutality" Renovation in Castlegar Castlegar deck builder Painter in Castlegar Facebook

07-14-2009, 03:06 PM	#4
Mike(VA) View Profile Mike(VA) Custom Stuff Send Message Follow Blogs (0) Threads (859) Photos (0) Reviews (0) Projects (0) Toolbox (0) View All Activity Custom Stuff Trade: General Contractor - Custom Renovations Join Date: Jan 2008 Location: Manassas, VA Posts: 859	Re: Puzzle Me This: You do not know whether the odd penny is heavier or lighter so dividing them into two piles tells you nothing. On the scale, is the side down the heavier one or the side up the lighter one? Hint: Flow charts work. __________________ __________________________________________________ ___________ I EXPECT THAT SOMEDAY I WILL SEE THE FRUITS OF MY LABOR. IS IT SOMEDAY YET? Clifton, Great Falls, McLean, Fairfax Station, Manassas, Virginia Renovation Contractor

07-14-2009, 03:39 PM	#5
Mike(VA) View Profile Mike(VA) Custom Stuff Send Message Follow Blogs (0) Threads (859) Photos (0) Reviews (0) Projects (0) Toolbox (0) View All Activity Custom Stuff Trade: General Contractor - Custom Renovations Join Date: Jan 2008 Location: Manassas, VA Posts: 859	Re: Puzzle Me This: Ok, selfcontract, try this one: Solve this using the following 15 clues: 1. There are five houses in a row, each of a different color and inhabited by people of different nationalities, with different pets, drinks, and flowers. 2. The English person lives in the red house. 3. The Spaniard owns the dog. 4. Coffee is drunk in the green house. 5. The Ukrainian drinks tea. 6. The green house is immediately to the right (your right) of the ivory house. 7. The geranium grower owns snails. 8. Roses are in front of the yellow house. 9. Milk is drunk in the middle house. 10. The Norwegian lives in the first house on the left. 11. The person who grows marigolds lives in the house next to the person with the fox. 12. Roses are grown at the house next to the house where the horse is kept. 13. The person who grows lilies drinks orange juice. 14. The Japanese person grows gardenias. 15. The Norwegian lives next to the blue house. So given the 15 clues, who drinks water? And who owns the zebra? __________________ __________________________________________________ ___________ I EXPECT THAT SOMEDAY I WILL SEE THE FRUITS OF MY LABOR. IS IT SOMEDAY YET? Clifton, Great Falls, McLean, Fairfax Station, Manassas, Virginia Renovation Contractor

07-14-2009, 05:27 PM	#6
maninthesea View Profile maninthesea Pro Send Message Follow Blogs (0) Threads (556) Photos (0) Reviews (0) Projects (0) Toolbox (0) View All Activity Pro Trade: High Pressure Air Join Date: Nov 2008 Location: guam Posts: 556	Re: Puzzle Me This: dont have time to work out all the details but the first step woudl be weigh 2 piles of 3. if they are the same then your bad penny is in the 4 you did not weigh. If they do not ballance then the bad penny is one of the 6 you did weigh.

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07-14-2009, 05:38 PM	#7
Mike(VA) View Profile Mike(VA) Custom Stuff Send Message Follow Blogs (0) Threads (859) Photos (0) Reviews (0) Projects (0) Toolbox (0) View All Activity Custom Stuff Trade: General Contractor - Custom Renovations Join Date: Jan 2008 Location: Manassas, VA Posts: 859	Re: Puzzle Me This: maninthesea is getting close. When you find the time, its challenging. __________________ __________________________________________________ ___________ I EXPECT THAT SOMEDAY I WILL SEE THE FRUITS OF MY LABOR. IS IT SOMEDAY YET? Clifton, Great Falls, McLean, Fairfax Station, Manassas, Virginia Renovation Contractor

07-15-2009, 07:30 AM	#8
maninthesea View Profile maninthesea Pro Send Message Follow Blogs (0) Threads (556) Photos (0) Reviews (0) Projects (0) Toolbox (0) View All Activity Pro Trade: High Pressure Air Join Date: Nov 2008 Location: guam Posts: 556	Re: Puzzle Me This: OK if 3 + 3 ballance then there are 4 left containing a bad penny. Put 1 + 1 on the scale. If they dont balance then bad penny is on the scales. Take lighter one off and replace with any one of the good pennies. If they balance then the one you took off was light. If the heavy penny is heavy again then its the bad heavy penny. If the 1 + 1 do ballance in the second weighing then bad penny is one of the other two. Swap one penny in. If un balanced then it is bad penny and it will show if it is light or heavy. If scales ballance then the remaining penny is bad and I have no Idea how to tell if its light or heavy without swapping it in.

07-15-2009, 07:49 AM	#9
maninthesea View Profile maninthesea Pro Send Message Follow Blogs (0) Threads (556) Photos (0) Reviews (0) Projects (0) Toolbox (0) View All Activity Pro Trade: High Pressure Air Join Date: Nov 2008 Location: guam Posts: 556	Re: Puzzle Me This: If 3 + 3 from step one dont ballance then other four are good bad penny is on hte scale. Pull the three from the heavy side and swap on of the light ones to the other side and add one good penny. If light side stays light then bad penny is there. and is light. pull one of those off and put good penny on other side. if still light then light penny is on the scale. if ballanced then the one you pulled was light. If scales ballance from step 2 then one of the three you pulled from the heavy side is heavy. try to ballance two of those. If not ballanced then heavy one is bad penny & Heavy. If they do ballance then the one you did not put on the scale is bad and heavy.

07-15-2009, 08:34 AM	#10
Mike(VA) View Profile Mike(VA) Custom Stuff Send Message Follow Blogs (0) Threads (859) Photos (0) Reviews (0) Projects (0) Toolbox (0) View All Activity Custom Stuff Trade: General Contractor - Custom Renovations Join Date: Jan 2008 Location: Manassas, VA Posts: 859	Re: Puzzle Me This: Hmmm.... you are not covering all possibilities. Pull the three from the heavy side and swap on of the light ones to the other side and add one good penny. At this point, you don't know if the bad penny is heavier or lighter and won't be able to tell which one and its difference. __________________ __________________________________________________ ___________ I EXPECT THAT SOMEDAY I WILL SEE THE FRUITS OF MY LABOR. IS IT SOMEDAY YET? Clifton, Great Falls, McLean, Fairfax Station, Manassas, Virginia Renovation Contractor

07-15-2009, 02:10 PM	#12
ChainsawCharlie View Profile ChainsawCharlie Crash Test Dummy Send Message Follow Blogs (0) Threads (2,206) Photos (1) Reviews (0) Projects (0) Toolbox (0) View All Activity Crash Test Dummy Trade: Landscaping Join Date: Jan 2008 Location: Kauai Posts: 2,206	Re: Puzzle Me This: ... edited for clarity Last edited by ChainsawCharlie; 07-15-2009 at 02:36 PM.

07-15-2009, 02:18 PM	#13
ChainsawCharlie View Profile ChainsawCharlie Crash Test Dummy Send Message Follow Blogs (0) Threads (2,206) Photos (1) Reviews (0) Projects (0) Toolbox (0) View All Activity Crash Test Dummy Trade: Landscaping Join Date: Jan 2008 Location: Kauai Posts: 2,206	Re: Puzzle Me This: edited for clarity Last edited by ChainsawCharlie; 07-15-2009 at 02:36 PM.

07-15-2009, 02:35 PM	#14
ChainsawCharlie View Profile ChainsawCharlie Crash Test Dummy Send Message Follow Blogs (0) Threads (2,206) Photos (1) Reviews (0) Projects (0) Toolbox (0) View All Activity Crash Test Dummy Trade: Landscaping Join Date: Jan 2008 Location: Kauai Posts: 2,206	Re: Puzzle Me This: Divide into three stacks. Step 1. Weigh two stacks. If they balance, Step 2. Swap one of the stacks out. If they still balance Step 3. Penny left out is the culprit. Weigh it against another penny. This will tell you if it is heavier or lighter. Now...If the first two balance in Step one Step 2. Swap one of the stacks out. If the scale tilts down, you know you have a heavy penny in this stack. If it tilts up, you know you have a light penny. Take this stack, split into three pennies. Step 3, Weigh two pennies. The scale will either tilt, telling you which penny is heavy or ligh, or it will balance, showing that the penny left out from this group is heavy or light. Finally- If the the first two stacks do not balance from the start (Step 1), Step 2. replace one stack. If you remove the heavy stack, and the scale remains out of balance, you will know you have a light penny in the side you did not remove. If the scale balances, you know you have a heavy penny in the stack you removed. Likewise, if you replace the light stack, and the scale reamins unbalanced, you know you have a heavy penny in the stack not swapped. If the scale comes into balance, you know you have a light penny in the stack you removed. Repeat step 3.,

07-15-2009, 03:56 PM	#16
Mike(VA) View Profile Mike(VA) Custom Stuff Send Message Follow Blogs (0) Threads (859) Photos (0) Reviews (0) Projects (0) Toolbox (0) View All Activity Custom Stuff Trade: General Contractor - Custom Renovations Join Date: Jan 2008 Location: Manassas, VA Posts: 859	Re: Puzzle Me This: Charlie said: Step 3, Weigh two pennies. The scale will either tilt, telling you which penny is heavy or light, This won't tell you which is the different penny. One could be heavy or the other one light. or it will balance, showing that the penny left out from this group is heavy or light. Good try, but if it balances at this point, that was your third try and it will take one more try to tell if the left over penny is lighter or heavier than the other 9. __________________ __________________________________________________ ___________ I EXPECT THAT SOMEDAY I WILL SEE THE FRUITS OF MY LABOR. IS IT SOMEDAY YET? Clifton, Great Falls, McLean, Fairfax Station, Manassas, Virginia Renovation Contractor

07-15-2009, 04:22 PM	#18
ChainsawCharlie View Profile ChainsawCharlie Crash Test Dummy Send Message Follow Blogs (0) Threads (2,206) Photos (1) Reviews (0) Projects (0) Toolbox (0) View All Activity Crash Test Dummy Trade: Landscaping Join Date: Jan 2008 Location: Kauai Posts: 2,206	Re: Puzzle Me This: If the first two are off balance in step 1 Step 2. If the right side stack is heavy and you replace it, one of two things will happen-the scale will still show heavy on the right, telling you both stacks you weighed on the right are the same, and that the left side has a light penny, or The scale will balance, telling you the newly added stack is the same as the left stack, which tells you the stack you removed from the right has a heavy penny. Got it? When you get to step three, you will already know what you are dealing with-light or heavy.

07-15-2009, 04:31 PM	#19
Mike(VA) View Profile Mike(VA) Custom Stuff Send Message Follow Blogs (0) Threads (859) Photos (0) Reviews (0) Projects (0) Toolbox (0) View All Activity Custom Stuff Trade: General Contractor - Custom Renovations Join Date: Jan 2008 Location: Manassas, VA Posts: 859	Re: Puzzle Me This: ok, I misread: Now...If the first two balance in Step one It was a matter of wordsmithing that I missed. My Dad gave me that puzzle when I was in the 9th grade and it took me about 4 weeks to figure it out. Drew out scales and options and everything. Guy never gave me any hints at all. He had others but I forgot them except the zebra one. He used to be a P-2 pilot doing coastal patrol and they passed their time doing these. Even today, I don't have the answer to hand out unless I solve it all over again. Don't know if you can find the answer on the net to this one but the zebra one is easy. Still took me a while when I was young. (No internet, then) __________________ __________________________________________________ ___________ I EXPECT THAT SOMEDAY I WILL SEE THE FRUITS OF MY LABOR. IS IT SOMEDAY YET? Clifton, Great Falls, McLean, Fairfax Station, Manassas, Virginia Renovation Contractor

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Mathematical Puzzle	maj	Off Topic (Non Trade)	11	10-06-2006 04:07 PM

07-15-2009, 04:58 PM	#20
ChainsawCharlie View Profile ChainsawCharlie Crash Test Dummy Send Message Follow Blogs (0) Threads (2,206) Photos (1) Reviews (0) Projects (0) Toolbox (0) View All Activity Crash Test Dummy Trade: Landscaping Join Date: Jan 2008 Location: Kauai Posts: 2,206	Re: Puzzle Me This: Scenario 1: split pennies into three stacks, set one aside. Step 1.Stack 1 on the left, stack 2 on the right. If they balance, Step 2. replace stack 2 with stack 3. If they still balance, all 9 pennies in 1,2 and 3 weigh the same. Step 3. weigh one of these pennies against penny 10. You will know whether it is lighter or heavier. ---------------------------------------------------------------------------------- Scenario 2. split pennies into three stacks, set one aside. Step 1. Stack 1 on the left, stack 2 on the right. if they balance Step 2. Replace stack 2 with stack 3. A. If the right side of the scale drops (stack 3) you will know stack three has a heavy penny. Split stack 3 into three individual pennies. Step 3. 1 on the left, 2 on the right, 3 set aside. If they balance, that tells you penny 3 heavy. If they do not balance, you will know which is the heavy penny. B. If the right side of the scale rises (stack 3), you will know stack three has a light penny. Step 3. 1 on the left, 2 on the right, 3 set aside. If they balance, that tells you penny 3 light. If they do not balance, you will know which is the light penny. -------------------------------------------------------------------- Scenario 3a: split pennies into three stacks, set one aside. Step 1. Stack 1 on the left, stack 2 on the right. Stack three will weigh the same as either Stack 1 or stack 2. Step 2. If stack two is heavy, Replace stack 2 with stack 3. If the right side remains heavy, then you know stack two and stack three weigh the same, therefor stack 1 has a light penny. ----------------------------------------------------------------------------------- Scenario 3b Step 1. Stack 1 on the left, stack 2 on the right. Stack three will weigh the same as either Stack 1 or stack 2. Step 2. If stack two is light, Replace stack 2 with stack 3. If the right side remains light, then you know stack two and stack three weigh the same, therefor stack 1 has a heavy penny. Step 3. 1 on the left, 2 on the right, 3 set aside. If they balance, that tells you penny 3 is the heavy penny. Sc. 2 and 3, you will have determined through process of elimination that the tenth penny (set aside) weighs the same as the two stacks of three that were equal in weight, and it doesn't need to be weighed. Maybe there is more than one solution to this puzzle? The method I listed above will give you the results in three steps, and you WILL KNOW-light or heavy.