並前往https://academy.snapask.com/zh-hk/post/%E6%9C%9F%E6%9C%9B%E5%80%BC-Expected-value-%E8%B3%AD%E5%8D%9A%E9%81%8A%E6%88%B2%E5%BF%85%E7%94%A8-%E6%A6%82%E7%8E%87%E9%80%B2%E9%9A%8E%E7%AF%87-0d64ad64e1ed