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Easy Savoury


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17 replies to this topic

#1 rookie1ja

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Posted 30 March 2007 - 07:45 PM

Easy Deduction - Back to the Number Puzzles
A teacher thinks of two consecutive numbers between 1 and 10 (1 and 10 included). The first student knows one number and the second student knows the second number. The following exchange takes place:
First: I do not know your number.
Second: Neither do I know your number.
First: Now I know.
What are the 4 solutions of this easy number puzzle?

This old topic is locked since it was answered many times. You can check solution in the Spoiler below.
Pls visit New Puzzles section to see always fresh brain teasers.


Spoiler for Solution


Spoiler for old wording

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#2 Red Hat

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Posted 15 June 2007 - 12:50 AM

What happened if the student A has the number five? Student B can have either the number 4 or 6, in which case he could guess that the other student has 3, 5, or 7. :rolleyes:
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#3 mrbojangles

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Posted 27 June 2007 - 11:13 PM

Honestly, when I tried doing this one, I never included 1 or 10 in the first place since the original problem says BETWEEN 1 and 10, meaning the numbers in question are 2 through 9. That might seem nit picky but these ARE brainteasers and it'd be nice if this one was clarified a little bit more. Also, I agree with the other person, what happens in the case of a 5? Why has that one been eliminated?
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#4 earl11

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Posted 05 July 2007 - 10:29 AM

If it was a 5, then the first one would not be able to say "Now I know". Instead, he would have said "I still don't know". Then, the 2nd person would know that the 1st person has either 4,5, or 6. If the 2nd person had a 3, 4, 6 or a 7, he would be able to say "I know now". But if he had a 5, he would still not be sure. And then the 1st person would know that the 2nd person has a 5.
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#5 courtneycater

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Posted 02 August 2007 - 07:42 AM

I can think of two situations but not four. If A has the number two, he knows B is either one or three. If B is one, B would KNOW A is two. Since B doesn't know, B must be three. The same would go for eight and nine

I'm getting addicted to these puzzles. I totally forgot to watch TV tonight. Anyone know where to find lateral thinking puzzles?
I guess I could look a little harder but I just can't put off watvching TV any longer
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#6 niilynn

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Posted 31 August 2007 - 01:33 AM

The questions asks "Will you find all 4 solutions?" The answer, then, should be "yes" or "no." There are a lot of riddles on here that ask that sort of question. The question SHOULD state, "what are the 4 solutions?"
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#7 rookie1ja

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Posted 31 August 2007 - 09:11 AM

The questions asks "Will you find all 4 solutions?" The answer, then, should be "yes" or "no." There are a lot of riddles on here that ask that sort of question. The question SHOULD state, "what are the 4 solutions?"


right ... so will you find all 4 solutions? yes or no? there are a lot of people writing the same as you, but just a few of them really answer it (and prove it)
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#8 eedray

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Posted 26 September 2007 - 11:47 AM

isn't this assuming alot?
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#9 BoilingOil

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Posted 26 September 2007 - 05:47 PM

I think I CAN see four solutions...

I'll call 1st person A, 2nd person B

A = 2, B = 3: A doesn't know at first. If B had 1, he would know. Since he doesn't know, he must have 3. A solves it at second round
A = 9, B = 8: analogous to the above.

A = 3, B = 4: A doesn't know at first. If B had 2, he would see that A could have only 1 or 3, but with 1, A would have known immediately. Therefor, since B doesn't know, he cannot have 2. A solves it at second round...
A = 8, B = 7: analogous to the above.

I'm still in the process of finding out what happens if A and B were reversed... Maybe there are even more than 4 solutions then :)

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#10 DechWerks

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Posted 09 November 2007 - 10:01 AM

I do not understand why 1 and/or 10 are 'easy' to guess. As this is pretty fundamental, I think this is why I missed this one.
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