X Data Science Intern interview questions

The interview process started with a coding assessment and moved into a technical interview. Beware that for the technical interview, they will tell you a description of a problem and throw you into hacker rank without a description there of the problem in hand. You need to listen carefully when the interviewer gives you the problem statement, or else you won't have anywhere to reference from.

I got a phone call interview arranged by recruiter, who got my resume from an ex-intern friend of mine. I did not sign anything and wasn't told not to divulge the questions, so I assume I can comment on what they were. First I had to solve a basic probability problem that turns into using Bayes rule. I'm terrible at solving combinatorial puzzles on the fly, but when the interviewer hinted the Bayes rule, I kind of successfully framed it as a posteriori calculation. I made a mistake when computing the denominator though. Then I was given the following question: given a 2-column file with user codes and counts, retrieve the top-k users based on a score that is a function of the number of times they appear on the file and these counts. My solution didn't match what I assume to be the "answer key", so the interviewer started walking me through the idea, but I didn't get there. No coding was asked for. I don't have the outcome right now, but I expect to be negative. Maybe some other time.