Inches is not the issue. It could be any units. The joke about the American vs Russian students was a jab at the American students, not the Russian ones! Someth

Inches is not the issue. It could be any units. The joke about the American vs Russian students was a jab at the American students, not the Russian ones! Something about the Russian students seeing something that American student couldn't. I don't agree with the premise of course, just providing the extra info as a hint. I can believe, however, that this problem was on a standardized test in US at some point. This last sentence points to the answer a bit more too :)