They're not supposed to be; the goal was to give Jews harder questions which had supposedly simple answers:
> One of the methods they used for doing this was to give the unwanted students a different set of problems on their oral exam. I was told that these problems were carefully designed to have elementary solutions (so that the Department could avoid scandals) that were nearly impossible to find.
They could also give huge boolean formulas, and ask the applicant to decide if it is satisfiable[1] or not. Simple yes or no answer, which is quite a hard (NP-hard) to come by.
While it is obvious that a satisfiable instance will have a simple yes-certificate, it is not known if for any unsatisfiable instance there is a short no-certificate (i.e. SAT is in NP, but believed not to be in coNP). The Jewish problems had to have simple solutions, while it could be hard to find a small proof of unsatisfiability of some large formula.
> One of the methods they used for doing this was to give the unwanted students a different set of problems on their oral exam. I was told that these problems were carefully designed to have elementary solutions (so that the Department could avoid scandals) that were nearly impossible to find.