Your question is Statistical Significance and Sample Size. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Explain the concept of statistical significance and how you determine the required sample size for an A/B test.
Your answer should distinguish statistical significance from practical significance, define alpha, power, baseline rate, and minimum detectable effect, and explain how these inputs determine sample size. Show the calculation for a two-arm proportion test, state key assumptions, and explain how you would validate the result and avoid common issues such as peeking or incorrect unit-of-analysis choices.