Compare:
A: The length of the hypotenuse of a right triangle with integer sides and with set of side lengths having an interquartile range of 2.
B: \sqrt{32}
This pulls in fundamentals from a couple topics at once.
Once you have the fundamentals down, centaur questions like this might be a more efficient way to find gaps, even if they’re less realistic? Just like compound movements make good exercises.
The problem here is that we don’t really deal with interquartile ranges on the GRE when the number of elements is not a multiple of 4.
This was partly inspired by your foundations quiz question asking about the minimum size of a certain set where all elements are distinct integers and IQR =/= range. When Greg works it he covers the use of IQR for n<4, which yeah I would have assumed was undefined if not for that discussion, I found it a bit quirky.
You could substitute range here and still get 99% of the value and less weird.
After posting this I did the 10 easy to hard problems for triangles and found another problem you have that similarly relies on knowing Pythagorean triples and checking properties in them, so this seems like a road that’s already been well traveled.
Experimenting with building questions still feels like useful practice, feels like it’s helping me spot red herrings faster.
This sounds like something you should be able to find an audience at r/GRE - just mention on the title that you wrote it.