WorldQuant Quantitative Researcher interview questions

first round is online assessment (need about 3-4 hrs to complete, all about math, a little bit difficult), after passing the first round, you will interview with HR, two quants (each for 30 minutes, asking behavior question, math question and brain teaser) -->?

40 questions to solve in 3 hours. The questions includes algorithm, probability, statistics, brain teaser, etc. Some of them are pretty easy but I think most of them require you to prepare enough to solve them.