If Party A, Party B and Party C sit together, they can be regarded as a whole X (tied together). At this time, it can be regarded as four people sitting casually (three people except A, B and C plus A, B and C X tied together). At this time, A44 sitting method is adopted, that is, 4*3*2* 1=24.
So the probability is 24/720= 1/30.
In teaching practice, I designed a table of fractional lines according to the "division and combination" of one-year series, and discussed it with th