Welcome to your interview.
The question is on your right: Two-Scale Heavier Sphere. 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 balance scale and 9 metal spheres. One of the spheres is slightly heavier than the other 8, which are of equal weight. How can you identify the heavier sphere using the scale only two times?