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        riddles >> easy >> glass half full riddle, my solution pleaseconfirm
        
(Message started by: octaz on Nov 17^th, 2012, 12:37pm)

Title: glass half full riddle, my solution pleaseconfirm
Post by octaz on Nov 17^th, 2012, 12:37pm

Hello Wu forums!

I'm new here, and I discovered you guys while trying to sharpin up on some CS skills for an upcoming java interview (any suggestions would be nice)

But that's not the point of this thread

My question is related to the half glass full riddle, and I have a possible solution to post. I would like confirmation if I am right, but not the solution if I am wrong! That's all the fun.

Here's the riddle if you haven't heard it:
You are in an empty room and you have a transparent glass of water. The glass is a right cylinder, and it looks like it's half full, but you're not sure. How can you accurately figure out whether the glass is half full, more than half full, or less than half full? You have no rulers or writing utensils.

I guess i'm gonna try to post it below in dark so i don't spoil it for anybody who doesn't know the answer (if I'm right!, and if i figure out how to post it hidden...)

[hide] With the glass full of water, do you invert it, holding your hand over the open end (so it does not spill), and a finger on the current level of water (with your other hand). After flipping, you observe the water level relative to your finger. If it is over your finger, then it is more then half full. If at the same level, even, otherwise, if below, it is less then half full[/hide]

Thanks for your time guys!

Title: Re: glass half full riddle, my solution pleaseconf
Post by towr on Nov 17^th, 2012, 2:05pm

There's a better, more reliable answer.

Here's (http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi?board=riddles_easy;action=display;num=1162599769) a previous thread on this puzzle.

Title: Re: glass half full riddle, my solution pleaseconf
Post by marlonmark on Jan 6^th, 2013, 10:28pm

Even i think thats the only possible answer

Title: Re: glass half full riddle, my solution pleaseconf
Post by rmsgrey on Jan 7^th, 2013, 5:01am

If you have a sealed container, with no caps or cups to catch air below or water above the water level, marking the water level, inverting it, and allowing it to reach equilibrium then comparing the new water level with the marked one would work.

Since you don't have the means to convert the glass into a sealed right-cylindrical container (your hand may or may not cover the open end, but is not all that flat either way) and a finger at the current water-level is only an approximate marker, you may want to find a more reliable way of judging the question.

Happily, there is one :)