In a city, when students take the physical and chemical experiment operation examination, they draw lots to decide their own examination contents. It is stipulated that each candidate must take part i

In a city, when students take the physical and chemical experiment operation examination, they draw lots to decide their own examination contents. It is stipulated that each candidate must take part in three physics experiments ( Method 1: The list grid is as follows:

Chemical experiment

Physical experiment D E FA (A, D) (A, E) (A, F)B (B, D) (B, E) (B, F)C (C, D) (C, E) (C, f) Method 2: Draw a tree diagram as follows:

All possible results AD, AE, AF, BD, BE, BF, CD, CE, cf;

As can be seen from the table or tree diagram, there are nine possible outcomes * * *, in which event M occurs once, so P (m) = 19.