[数学]確率
https://drive.google.com/file/d/18KipA1rnUz54TGVoMTJjfez52j7cgwcI/view?usp=drivesdk
https://drive.google.com/file/d/1qGuYGpjVDoUc8owDLr_yHKOCZmXL0rO8/view?usp=drivesdk
https://drive.google.com/file/d/1wn02hz6jD4mzTDXvxdLA2EV0sjvLTxH7/view?usp=drivesdk
