Except that some interviewers say that when they hear "I don't know" it's a sign that the interviewee gives up easily and extrapolates that they will give up easily when they encounter problems while working. The point is that as an interviewee you're supposed to "know" an unfair amount of knowledge and have incredible spontaneous algorithmic skills to boot (the interviewer picks 1 question and has the answer while the interviewee anticipates and is expected to competently answer the set of all possible questions). What ends up happening is everyone crams for interviews by rote memorizing common system design and coding questions. From the interviewee's side it's a "damned if you do, damned if you don't" scenario when OP asks his trick question. This is similar to hazing where initiates are unsure of the correct way to conduct themselves because they are being judged by some vague, perhaps intentionally withheld ideal, standard, or cultural archetype. I'd imagine disenfranchised groups would disproportionately 'fail' this question, as they are already insecure of their belonging in tech culture
