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So i think to spice up the stale(brain intensive wise) general forum w/ some recreational math.
I'll post new rounds once in awhile, but only when the answers are all clear and up.
Sometimes I would know the answer and sit out, other time I would not know the answer and I'll jump in and participate too :D
Today as first day, I know the answer, so I won't participate yet.
Enuf fluff, let's get to business:
This problem is simple algebra, and it is as follows:
How many coconuts?
Five men and a monkey were stranded on strangee island, where common sense may be false while math/logic is always true.
For food, they gather up a bunch of coconuts, then they all went to sleep.
For simplicity, let's call these five men A B C D E, perspectively.
In the middle of the night...
A wakes up, and he thinks he ought to divide up the coconuts. He looks at the pile of coconuts and he realizes that if he remove one coconut, the pile can be evenly divided into 5 equal parts.
So A takes a coconut, and gave it to the monkey. He then divides the rest of the coconut into equal 5 parts, and keeps one part for himself, and leaves the rest of the coconut out. He goes back to sleep.
B wakes up, and he thinks he ought to divide up the coconuts. He looks at the pile left out in the open, and he realizes that if he remove one coconut, the pile can be evenly divided into 5 equal parts.
So B took a coconut and gave it to the monkey. He then divides the rest of the coconut into equal 5 parts, and keeps one part for himself. He leaves the rest out and he goes back to sleep.
C, D, E each wakes up, divides, and goes back to sleep consecutively afterwards. Each of them finds that if you remove one coconut, the rest can be divided into 5 equal parts. So each of them does the same procedure as A and B.
Day break...
Monkey is happily dancing with his 5 coconuts, unknowing how they got there.
All men woke up, and saw still some coconuts left out.
Each man compares his own coconuts with each other, and they find that they have equal amount of coconuts for himself.
How many coconuts are there to begin with so this could happen?
+ Show Spoiler [rewording the problem, no spoiler here] +
So to reword the problem, it is like this:
in the beginning one pile of coconuts
each of the five men does this procedure on the one pile consecutively:
takes one from the pile and give it to monkey, divides rest into 5 equal parts, keep one part for himself, leave the rest and go to sleep.
As a result:
there are still some left in the one pile
the monkey ends up with 5 coconuts
the men all have equal number of coconuts
Good Luck!! I'll post hints and answers if nobody got them, in the mean time discuss and tackle it! Communicate ideas and let's work that brain muscle. try to tag spoilers if you feel your answer is right :p
i'll be sleepa now, checking back tomorrow, gl!
+ Show Spoiler [mysolution] +
We know all the men had equal coconuts, so let X be that number
We have five men, so then all the men have 5X coconuts total
Monkey has 5
There are some remaining, call that R
So total amount will be 5X + R + 5
Now, some funny property of this thing... the number, when subtracted by 1, can be divided by 5 evenly, and not just evenly, but equal to X(since all men ends up with equal number of coconuts). So:
5X + R + 5 - 1 = 5X
Now we cancle the 5X on each side and have
R = -4
After the first guy took his share of coconuts, and gave one to the monkey, the total pile is
4X + R + 4
The second guy realizes this also, when subtracted by 1, can divide by 5 evenly, and not only evenly, but equal to X as well. So:
4X + R + 4 = 5X + 1
R + 3 = X (since R = -4)
X = -1
And we have the total number of coconuts,
5X + R + 5 = 5(-1) + (-4) + 5 = -4
Now to see why it works, it's quite interesting:
The pile is -4, first man wakes up, he toss a positive coconut to the monkey, so the pile is not -5. The man divides the pile into 5 parts, so each part is -1. Man then takes a pile, so man gets -1, and the total pile remains -4, as if nothing ever happened.
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Recreational math, huh? Also synonymous with cruel and unusual punishment
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On June 23 2008 20:34 DanceCommander wrote:
Recreational math, huh? Also synonymous with cruel and unusual punishment
Then sit out my friend, it is not for the faint minded.
edit: English is not first language here
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On June 23 2008 20:35 evanthebouncy! wrote:Show nested quote +On June 23 2008 20:34 DanceCommander wrote:
Recreational math, huh? Also synonymous with cruel and unusual punishment Then sit out my friend, it is not for the feint minded.
Brb making a [recreational english grammar] thread.
First challenge.
HOMONYMS
Faint vs Feint.
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+ Show Spoiler +
At first I thought the phrasing was wrong and that it was impossible for the men to all have the same amount of coconuts at the end...
Then I did the math (trying to prove the phrasing was wrong) :
That would mean that (x-1)/5 = (4x-9)/25 = (16x-61)/125 etc...
Which works for x = -4
<<
on a strange island, where common sense may be false while math/logic is always true.
>>
So there are -4 coconuts in the stack. a men comes up gives one to the monkey which makes -5 coconuts. He takes on fifth and leaves the rest -> -4 coconuts left.
Second man does the same -> same result etc...
Am I right ?
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+ Show Spoiler +How can E have the same amount as A if the pile is always reduced before it gets to E? If the number is always divided by 5, E can't have the same amount as A.
haha just saw Beamo's. Clever.
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+ Show Spoiler +Not to take away from the problem, because the answer appears to be quite clever, but...
"Common sense may be false while math/logic is always true."
Logic dictates that in a real-life scenario like this, you cannot have a negative number of anything tangible, like coconuts are. It might be better to reword it as something like "There is an island. On it, typical math is always true, but other aspects of reality might not be that way..." Now I'm sure someone could find fault with this, too, but I just came up with it in 10 seconds. I'm sure there's a much better way to phrase the statement.
But anyway, good job on the question. Just be careful if someone comes up and says "Alright, logic is true, so the people have to have -some- real coconuts."
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Seems impossible that they each take approx 1/5 off the entire stack, yet end up with the same amount of coconuts in the end...
var x = amount of coconuts left in the end;
for (i=0;i<5;++i)
x *= 1.25 + 1;
totalstack = x;
You're only using ints, so amount left in the end must be divisible by 4.
Doing x * 1.25 + 1 must yield a new number again divisible by 4, and this must be repeatable 5 times. Tryout:
4 -> 6 X
12 -> 16 -> 21 X
28 -> 36 -> 46 X
60 -> 76 -> 96 -> 121 X
Can't be arsed to go on, it'll be a big number. But still, not all of the guys will have the same number of coconuts, i don't see how that's possible? Or did you leave out the ninja in the story?
Guess i'm not smart enough to see through this. But if each guy eats half the pie that the last one left behind, no-one will eat the same amount of pie, right? Enlighten me, geniuses of TL!
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Ok lolz, if that is the correct answer, hats off to you. Would have never occurred to me...
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Aotearoa39261 Posts
On June 23 2008 21:50 Beamo wrote:+ Show Spoiler +
At first I thought the phrasing was wrong and that it was impossible for the men to all have the same amount of coconuts at the end...
Then I did the math (trying to prove the phrasing was wrong) :
That would mean that (x-1)/5 = (4x-9)/25 = (16x-61)/125 etc...
Which works for x = -4
<<
on a strange island, where common sense may be false while math/logic is always true.
>>
So there are -4 coconuts in the stack. a men comes up gives one to the monkey which makes -5 coconuts. He takes on fifth and leaves the rest -> -4 coconuts left.
Second man does the same -> same result etc...
Am I right ?
Same method, same result 
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I don't get why this is fascinating to some people. I'll close the topic in a few seconds and you rather crack your brain for a couple of hours/minutes with no use at all in your whole life, what the?
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As has already been posted, must be -4, as the human gain must in each partition be equal to the the one coconut given to the monkey.
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On June 23 2008 23:16 ForAdun wrote:
I don't get why this is fascinating to some people. I'll close the topic in a few seconds and you rather crack your brain for a couple of hours/minutes with no use at all in your whole life, what the?
A few minutes of brain exercise can´t hurt, you know. My maths skills did decline a lot in recent years due to a lack of exercise. But I admit solving this riddle was rather boring.
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hahaha, i got to the answer -4 but thought i was just wrong >_<
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Well I don't see how it is brain exercise if you find the answer being -4 because -4 doesn't exist which takes about 1 brain cell to realize so when you realize that the answer is impossible after 1 minute of reading instead of saying the answer must be -4 you're way smarter and therefore you should have more brain capacity than anyone who gives the "correct" answer. Just my 50 cent.
Math is........ well, just not good for your health.
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i wonder if i'm the only one that read the title as "recreational meth"
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On June 24 2008 00:42 anotak wrote:
i wonder if i'm the only one that read the title as "recreational meth"
make a new thread about it.
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Well done folks! We have a rather small audience pool at the moment but I'll keep going with more later on today/this week when I find more funny ones.
I'll post my solution in the op now.
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On June 23 2008 20:53 Ack1027 wrote:Show nested quote +On June 23 2008 20:35 evanthebouncy! wrote:On June 23 2008 20:34 DanceCommander wrote:
Recreational math, huh? Also synonymous with cruel and unusual punishment Then sit out my friend, it is not for the feint minded. Brb making a [recreational english grammar] thread. First challenge. HOMONYMS Faint vs Feint.
ROFL
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On June 23 2008 20:30 evanthebouncy! wrote:+ Show Spoiler [mysolution] +
We know all the men had equal coconuts, so let X be that number
We have five men, so then all the men have 5X coconuts total
Monkey has 5
There are some remaining, call that R
So total amount will be 5X + R + 5
Now, some funny property of this thing... the number, when subtracted by 1, can be divided by 5 evenly, and not just evenly, but equal to X(since all men ends up with equal number of coconuts). So:
5X + R + 5 - 1 = 5X
Now we cancle the 5X on each side and have
R = -4
After the first guy took his share of coconuts, and gave one to the monkey, the total pile is
4X + R + 4
The second guy realizes this also, when subtracted by 1, can divide by 5 evenly, and not only evenly, but equal to X as well. So:
4X + R + 4 = 5X + 1
R + 3 = X (since R = -4)
X = -1
And we have the total number of coconuts,
5X + R + 5 = 5(-1) + (-4) + 5 = -4
Now to see why it works, it's quite interesting:
The pile is -4, first man wakes up, he toss a positive coconut to the monkey, so the pile is not -5. The man divides the pile into 5 parts, so each part is -1. Man then takes a pile, so man gets -1, and the total pile remains -4, as if nothing ever happened.
Do you mean 'now'?
cuz it makes a difference
actually, not that big of a difference cuz i could figure out what you meant
love this thread, interesting stuff, and im actually gonna try to do the next one
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+ Show Spoiler +logically its impossible, you cannot take a fifth of a number, leave 4/5-1 and then break up 4/5 into fifths and have it be equal to the original 1/5. 1/5X + 4/5X=X+1 where the 1 is to the monkey you cannot then take out the 1/5X, leaving 4/5X, with the monkey also having one then, with the 4/5X, subtract one, 4/5X -1 and divide it into five parts going on this way you cannot have equal stacks in the end of each man takes his portion out at the time he separates them  if math and logic are true, math always says you cannot have negative length or negative objects :|
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On June 24 2008 00:31 ForAdun wrote:
Well I don't see how it is brain exercise if you find the answer being -4 because -4 doesn't exist which takes about 1 brain cell to realize so when you realize that the answer is impossible after 1 minute of reading instead of saying the answer must be -4 you're way smarter and therefore you should have more brain capacity than anyone who gives the "correct" answer. Just my 50 cent.
Math is........ well, just not good for your health.
Hey thanks Im gonna write that in my math tests from now on.
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On June 24 2008 12:22 Gene wrote:+ Show Spoiler +logically its impossible, you cannot take a fifth of a number, leave 4/5-1 and then break up 4/5 into fifths and have it be equal to the original 1/5. 1/5X + 4/5X=X+1 where the 1 is to the monkey you cannot then take out the 1/5X, leaving 4/5X, with the monkey also having one then, with the 4/5X, subtract one, 4/5X -1 and divide it into five parts going on this way you cannot have equal stacks in the end of each man takes his portion out at the time he separates them if math and logic are true, math always says you cannot have negative length or negative objects :|
You're not making yourself too clear.
To me it seems the idea is that X = (X - 1) * 4/5
Which is true for -4.
And everyone gets the same (negative) amount of coconuts.
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EPT![[image loading]](http://farm2.static.flickr.com/1055/531504215_92c97bb5ca.jpg)
