Bonsoir, réponse ci-joint

Explications étape par étape:

figure 1:

1/4 + (1/4×1/2) + (1/4 × 1/4) = 1/4 + 1/8 + 1/16 =

4/16 + 2/16 + 1/16 = 7/16

figure 2:

1/3 + (1/3 ×1/2) + (1/3 + 1/3) = 1/3 + 1/6 + 1/9 =

3/9 + 1,5/9 + 1/9 = 5,5/9

figure 3

1/4 + (1/4×1/2) + (1/4 × 1/6) + (1/4 × 1/6) =

1/4 + 1/8 + 1/24 + 1/24 =

6/24 + 3/24 + 2/24 = 11/24