Welcome to your interview.
The question is on your right: Expected Draws to Get All Red. Take a moment with it first.
Talk your thinking through with me if you like - when you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes). Discussion and graded submissions share your five interviewer interactions, so spend them well.
You have a bag with 3 red marbles and 7 blue marbles. You draw marbles one by one without replacement. What is the expected number of draws required to pull all 3 red marbles?