## My 12 year old student and I have been making a puzzle site

A forum for good logic/math puzzles.

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### Re: My 12 year old student and I have been making a puzzle s

quintopia wrote:In any case, Qaanol's experiments have proved to my satisfaction that it is possible to cook the egg to the equivalent of the 6 contiguous minute egg in under 10 minutes (by doing the official 9 minute solution with a quick cool-down and slow warm up in the three minute delay, plus a little bit more just to finish). In the future I will accept as correct any value strictly less than 10 minutes.

What? The principle behind the puzzle is that we have no ability to measure the passage of time except by the hourglasses. This means between the 4 and 7 minutes after the start, we cannot measure subintervals whatsoever. There’s no way to accurately, reliably, and repeatably control the cooling and warming of the egg in that period.

Furthermore, even the use of a bowl of water in any capacity violates the spirit of the puzzle. The idea behind a logic puzzle is that everything necessary for and permissible in the solution of the puzzle gets included in the statement of the puzzle. If your solution requires things besides hourglasses and boiling water, I strongly object. I mean, if you allow ice water, what’s next? Creating a pendulum using kitchen utensils, counting oscillations during the first four minutes, and allowing half that many more oscillations beyond, for a total of six minutes?

I think it’s a clever puzzle both ways. When it needs to be done continuously, it shows a shorter time interval may take longer to measure. When non-continuity is allowed, that is a clever twist on its own.

As I mentioned before, if you want to allow non-continuity, I’d change the question. My suggestion was “You need to put enough sand in an hourglass to make a 6-minute timer. How quickly can you do so?”
Small Government Liberal

Qaanol

Posts: 2393
Joined: Sat May 09, 2009 11:55 pm UTC

### Re: My 12 year old student and I have been making a puzzle s

This looks nice, but pleeeease add a second M to "comunity" on the main page. It's burning my eyes!

Btw, I found that one hard:
The Cofoundry wrote:A man has 5 coins in his pocket.
He can make 13 different amounts of money with his coins.
The amounts of money he can make end with one of two possible digits
He cannot make up exactly 70 pence
He cannot afford an item costing 1 pound
He can make a prime number bigger than 10 with his coins.
What coins does the man have?
(Note: This man lives in Brittan, so the coins he may have in his pocket are 1p, 2p, 5p, 10p, 20p, 50p, and 1 Pound).

But I think I nailed it:
Spoiler:
Can't afford 1 pound -> scratch that 1 pound coin, can't have 2x50p
Ends with one of two possible digits -> has only one of the 1p/2p/5p group (which I probably wouldn't know how to prove)
Can make a prime number bigger than 10 -> the coin from the above group is 1p
Cannot make up exactly 70p -> can't have 20p and 50p
If you have a 50p, you can only have 10p coins, but that would allow you to make 70p so there's no 50p
3x 20p and 1x10p allows you to make 70p, so there are only 2 possible solutions:
1/10/10/10/20 and 1/10/10/20/20
I can't remember combination calculations, so I count the possibilities and find that it's 1/10/10/10/20
Yay!
Bertrand Russell wrote:Not to be absolutely certain is, I think, one of the essential things in rationality.
Richard Feynman & many others wrote:Keep an open mind – but not so open that your brain falls out

jules.LT

Posts: 1476
Joined: Sun Jul 19, 2009 8:20 pm UTC
Location: Paris, France, Europe

### Re: My 12 year old student and I have been making a puzzle s

Qaanol wrote:As I mentioned before, if you want to allow non-continuity, I’d change the question. My suggestion was “You need to put enough sand in an hourglass to make a 6-minute timer. How quickly can you do so?”

Thinking about this again, this particular task can be performed in less than 9 minutes. If you want the 9-minute answer, I’m not sure what a good wording for that puzzle would be.
Small Government Liberal

Qaanol

Posts: 2393
Joined: Sat May 09, 2009 11:55 pm UTC

### Re: My 12 year old student and I have been making a puzzle s

Um, it looks like there's a ton of spam on the site. I got 6 messages consisting of the word "hi" from user blue100. Also even though most of the puzzles recently submitted were jibberish, two of those that weren't are duplicates.

I really like this site and its format, but there needs to be a bit more quality control for puzzle submissions in my opinion. How about having puzzle submission ranks, where some number of senior members have to approve puzzles from junior members, until the junior member has submitted enough accepted puzzles to be ranked higher? This will also help with the problem that it's tough to make sure that your puzzle hasn't already been submitted - I was hesitant in submitting my own puzzles until I had solved or at least looked at every puzzle on the site, because I didn't want to submit a duplicate.
Avin

Posts: 90
Joined: Sun Nov 25, 2007 3:08 am UTC

### Re: My 12 year old student and I have been making a puzzle s

We've been moderating the spam best we can. Trying to balance between discouraging users and preserving content.

New version of the site fixes this in many ways. First, puzzles ranked low enough don't provide ANY points for solving or submitting. Second, the list on the front page is not merely ordered by latest meaning that a puzzle needs to gain a little bit of popularity before it appears on the front page.

The new code also has the beginnings of user based moderation. Once your score gets high enough, you gain permissions for editing other peoples puzzles, etc.
lacitpo

Posts: 18
Joined: Thu Oct 18, 2007 2:08 pm UTC

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