Author Topic: Math problem that went viral.  (Read 10384 times)

leeway

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Re: Math problem that went viral.
« Reply #10 on: April 16, 2015, 12:57:23 PM »
nice python script. and also good collection of the math puzzles


rkbabang

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Re: Math problem that went viral.
« Reply #11 on: April 16, 2015, 01:16:40 PM »
Edit: yes, there is a single solution that follows from the inferences of conversation between P & Q.

I wrote a Python script and got the answer. It would be somewhat hard, but possible to do it by hand.

If anyone wants spoilers the answer is also at http://www.mathpropress.com/archive/iams/vol14.ascii

Now back to wasting my workday on other non-productive endeavors like value investing  8)

duh,   I see where I messed up.  For some reason I was thinking M couldn't be prime, but it is S that can't be the sum of primes.
Thanks for the solution.

matjone

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Re: Math problem that went viral.
« Reply #12 on: April 16, 2015, 04:44:29 PM »
this one is relatively straight forward with this type of problems. I just spent an evening and more to solve a similar but much more complicated problem:
2 numbers a and b, a >=b, both integers between 2 and 99. Mr. P knows the sum S=a+b, and Mr. Q knows the product M=a*b. Here is the conversation:
Q: I don't know what are a and b.
P: I know you don't know, and I don't know either.
Q: I know now.
P: I also know now.

What are a and b?

are we supposed to be able to do this in our head?

when p said "i know you don't know" I am guessing that meant he knew q didn't know it before q said anything, right?

Jurgis

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Re: Math problem that went viral.
« Reply #13 on: April 16, 2015, 10:14:51 PM »
this one is relatively straight forward with this type of problems. I just spent an evening and more to solve a similar but much more complicated problem:
2 numbers a and b, a >=b, both integers between 2 and 99. Mr. P knows the sum S=a+b, and Mr. Q knows the product M=a*b. Here is the conversation:
Q: I don't know what are a and b.
P: I know you don't know, and I don't know either.
Q: I know now.
P: I also know now.

What are a and b?

are we supposed to be able to do this in our head?

when p said "i know you don't know" I am guessing that meant he knew q didn't know it before q said anything, right?

If you can do it in your head, you're pretty genius level.
I'd suggest pen and paper at least, programming makes this easier though. I got almost to the end with pen and paper, but programming script makes last step easier to verify and doublecheck.

The answer to your second question is "yes".


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matjone

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Re: Math problem that went viral.
« Reply #14 on: April 18, 2015, 12:18:24 PM »
i am not a programmer.  I was trying to do it with excel but I am not sure it is up to the task

Does the order matter? If it is 6 then you know your numbers are 2 and 3, but you don't know whether it's a=2, b=3, or the other way around.

Jurgis

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Re: Math problem that went viral.
« Reply #15 on: April 18, 2015, 03:19:15 PM »
i am not a programmer.  I was trying to do it with excel but I am not sure it is up to the task

Does the order matter? If it is 6 then you know your numbers are 2 and 3, but you don't know whether it's a=2, b=3, or the other way around.

From the problem:

2 numbers a and b, a >=b,

Good luck
"Human civilization? It might be a good idea." - Not Gandhi
"Before you can be rich, you must be poor." - Nef Anyo
"Money is an illusion" - Not Karl Marx
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Lowlight

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Re: Math problem that went viral.
« Reply #16 on: April 19, 2015, 10:01:24 AM »
Am I the only one who doesn't see the answer in the link?  I would like to check what I came up with.  Someone message me the answer?  Or should I simply post my guess?

Pretium

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Re: Math problem that went viral.
« Reply #17 on: April 19, 2015, 12:29:44 PM »
Am I the only one who doesn't see the answer in the link?  I would like to check what I came up with.  Someone message me the answer?  Or should I simply post my guess?

http://mashable.com/2015/04/13/math-is-hard/
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