In a chess game in which A, B and C participate, the game is played according to the following rules: the first game: A versus B; The second game: the winner of the first game.

Then the result of the four games is: the first game: B wins A; The second game: B wins C; The third game: B wins A; The fourth game: B wins C.

Then p (a) = (1-0.4) × 0.5 × (1-0.4) × 0.5 = 0.09,

(2) Let C win three games in a row as event B, and discuss it in two situations:

(1), if B wins A in the first game; Then the second game: C wins B; The third game: C wins A; The fourth game: C wins B.

Its probability p1= (1-0.4) × (1-0.5 )× 0.6 × (1-0.5),

(2) If A wins B in the first game; Then the second game: C wins A; The third game: C wins B; The fourth game: c wins a.

Its probability P2=0.4×0.6×( 1-0.5)×0.6,

Then p (b) = p1+p2 = (1-0.4 )× (1-0.5 )× 0.6× (1-0.5)+0.4× 0.6× (/kloc-)