Bonjour pouvez vous m aidez svp pour l exercice 2 merci d avance

bonjour
R:revers
D; droit
                   1 ére balle            2émé balle              3 émé balle
                                                                                     R                 RRR
                                                     R
                                                                                     D                 RRD
                         R
                                                     D                              R                RDR
                                                                                      D                RDD

                                                                                     R                 DRR
                                                   R
                                                                                     D                  DRD
                      D
                                                  D                                R                     DDR
                                                                                    D                   DDD

6 issues

3 fois du meme coté
DDD
et
RRR
2 issues
2 sur 6
P(3fois m^me coté)=2/6=1/3