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Wrong puzzler answer on Jan 22

I think that jt1979 gets the credit for the correct data to show that the COM and the 1/4 line are about a quarter inch apart for the 20" circular tank. I hope that any naysayers will now “show their work” and will go to the effort to prove their work mathematically. We’ve seen a lot of handwaving arguments that are so vague that they are meaningless.

Now, will Tom and Ray take back that $26 prize for the wrong answer?

Does this hold water (pun intended)?

Does this make sense?

I think I followed your instructions shown in your attachment, but the areas produced are not equal according to Google SketchUp (see my attachment). What made you think they would be?

I was thinking that by adjusting by ‘cutting off’ the bottom arc of my folded piece, this would adjust the the bisecting line up by the correct amount to make the volumes even. Seemed like I could use the materials at hand (no compass) to get to a geometrical solution. Guess I could’ve marked it up like you did. Thanks.

I don’t think so. In fact, it looks like that method actually gives you a line that’s above (and therefore, farther from the true answer) than drawing a line through the center of gravity.

Exactly right. The error in the incorrect answer corresponds rather exactly to mistaking the average (or “expected value”) of a probability distribution for its median.

I see that I responded to this thread numerous times starting in 2011. My username has changed slightly. I can see that I was a lot smarter in 2011. Maybe I need to yet again change my username to something even more descriptive.

Reminds me of the mango puzzler: “You can’t do it unless the number is two.”

That answer was correct, but not the only correct answer as originally stated.