I would say two days are needed to prepare for a Machine learning Interview. When I was preparing for an ML interview, I used to make a plan like how much I need to spend time on each topic. Machine learning Interview would totally revolve around the basics of coding, probability, statistics, machine learning modeling, and performance evaluation of models. I used to take notes while reading itself so that it helps in revising. I allot 3 hours for each subject and used to spend 6 hours each day. I could refer all these topics in two days.
You can check out this blog on Machine Learning Interview Questions by Intellipaat that covers frequently asked questions in Machine learning Interviews.
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This video on ML interview questions by Intellipaat will act as a catalyst for your Machine learning interview preparation: