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High school mathematics compulsory 3 probability examples. Example 1 Why are there ten ways to get three balls from five balls? Please do a tree analysis.
There are five choices for the first ball, four choices for the second ball and three choices for the third ball from the remaining four, and ***5*4*3=60 choices.
But we don't actually distinguish the order of the three balls, that is, the order of the three balls is different (3! =3*2* 1=6) is actually a method, so the total method is 60/6= 10.