Were these questions for entrance from high school or a bachelors program?
If the latter, many (say half) of them are acceptable, but if the former then none of them are.
If the latter, many (say half) of them are acceptable, but if the former then none of them are.
Now, after thirty years, these problems seem easier. Mostly, this is because the ideas of how to solve these problems have spread and are now a part of the standard set of ideas. Thirty years ago these problems were harder to solve and, in addition, the students were given these problems one after another until they failed one of them, at which point they were given a failing mark.
And then there's two levels of competition past that I never made it to... just 1... damn... question... short...
I got a perfect score on the AIME in 1998, but they didn't let Canadians write the USAMO back then. :-(