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Google L3 DS Interview Experience


  1. Recruiter screen and questionnaire
  2. Technical phone interview
  3. Onsite interview (over video call) - 4 rounds


  • Always consider and mention assumptions
  • Code with the fewest lines of code to prevent redundant or ugly code
  • Try your best to provide at least 2 solutions

Technical phone interview question

  1. You have 100 coins in a box and 99 are fair. What is the probability that the coin is not fair after flipping an unknown coin and ending up with heads?
  2. Follow up: What about 1000 coins in a box and 999 are fair?
  3. How do you check if a coin is fair or not?

Prep concepts:

  • Statistics: probability theory, hypothesis testing, regression, modeling, Bayesian methods, time series analysis, experimental design, decision trees
  • Computational skills

Hope this is helpful!


I think 2 solutions is very aggressive. I mean, there’;s just not that much time in an interview. If you mean providing some alternative suggestions, then I’m all with you.

Good rephrasing. Thanks for catching that.