Few Hr calls prior and between. First round: Probability questions, questions on general ml knowledge: lasso, ridge, mathematical justification of gradient descent, prob inequalities, linear algebra and geometric interpretations of probability. Final Onsite: Leetcode problems, stats, harder probability problems, deeper into ml knowledge: linear regression basics, pca, linear algebra, questions on the classes you have taken. ML knowledge is very much needed.

Well organized process: first round covered resume walkthrough, probability, and combinatorics. Final round included deeper probability questions, a data interview, and an HR discussion. Overall, a structured and positive experience.