Yep, have seen this one before. If you make the assumption that, because the diameter of the hole isn't stated, it isn't relevant, and the answer is therefore the same for /any/ (hint, hint!) value, the solution using algebra is straightforward. That assumption is correct, and so is the solution it produces ... but you can't /prove/ that without calculus. On 3/7/2022 3:30 AM, discuss-request@lists.openscad.org wrote: > > On Sat, 2022-03-05 at 14:29 +0000, Raymond West wrote: >> My understanding is that 'z fighting' indicates a situation where >> there is some indecision as to which of the two or more of the >> 'fighting faces' should be used. In the physical world, it is the >> same, you would not bore a hole exactly the same depth as the >> workpiece, the result will not be what you may expect. I believe is >> is good practice to avoid these sort of errors, even if the object >> renders OK to an stl, say. > This brings to mind a puzzle I read when I was a teenager. > > If you bore a hole through the center of a sphere such that the length > of the hole is 6", what is the volume of the remaining material?