Welcome to your interview.
The question is on your right: Prefix Sums for Range Queries. 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.
Given an array of integers, implement an efficient algorithm to find the prefix sum and explain how it can optimize subsequent range sum queries.