https://www.quora.com/Are-there-any-examples-of-hard-Chinese...
By the way, SAT Math questions are generally considered a piece of cake by most good students in East Asia (and they often get 800 or close without much extra preparation), which says something about the level of average American high school math education.
The SATs are simple math. The GREs are as simple, which is presumably four years farther along than the SATs. However, it's hard answering all those questions correctly in the given time frame (presumably). You'd need a randomly sampled set of chinese kids taking the SATs to see where they fit against our distribution of scores to draw further conclusions. Bear in mind, too, top american students are studying advanced math in high school (advanced meaning, enough to reasonably answer the questions on the quora page, with time to practice and get used to things like the proof questions)
Note: I'm not trying to justify the american education system, just providing commentary and trying to level the comparison a bit.
Note that fewer percentage of Chinese youths attend high school than American, so that might skew the comparison.
Anyway, don't mean to argue - it does appear on the news a lot "the chinese are out mathing us! America sucks!" with some political finger pointing, and my reaction is usually a facepalm coupled with wondering how controlled the comparison is.
0/4, none of these are really under the aegis of the Beijing regime - and while it is flattering of you to compare the entirety of the population of four countries with 40 million people to the single most selective school in the US, it is rather inaccurate to do so.
If you look closer, PISA 2015 also had China in there, where the four provinces Jiangsu, Guangdong, Beijing, and Shanghai participated. Now poor illiterate migrants' kids might not get hukous to Beijing schools, so you might be right that this might be slightly biased - but even these four richer provinces have nearly the population of the US, so even if only 200 million Chinese are "outmathing us", it still makes a massive difference.
See: http://ncee.org/2016/12/pisa-2015-results/
The range of schools in PISA is much broader than the top sliver of students in Phillips Exeter etc you mentioned.