Intellectual game: Weighing oil without a scale! Taoii’s Blog

Taoii's Blog: Mainly collects some interesting math problems, fun facts about mathematics, and mathematical methods, etc. The blog has only been established for a short time, and I haven't had much exchange with friends from all over. Yesterday, I suddenly had an idea to play a game related to the specialty of my blog with everyone. This game is just one question, with many solutions, you can use any method you want. But there is one point: I hope someone can find the optimal solution.