Your question is Currency Conversion System Design. 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).
Design a currency conversion API system.
Explain the API contract, rate ingestion and normalization, storage, caching, consistency model, and failure handling. Treat rate selection and anomaly detection as ML-assisted components where appropriate, and cover online serving, batch processing, monitoring, and evaluation.