please send solution asap Z = 4 if needed

Consider an emergency center of a hospital where patients who have suffered road 10 accident are brought for emergency treatment. These patients suffer accident and are brought to the emergency from three main roads in the nearby area. If it is known that following are the probabilities that the accidents are taken place on the individual roads Road1: P1=2/9, Road2: P2=1/6, Road3: P3=11/18 What is the probability that six randomly arriving patients in the emergency center are distributed in the following fashion? Road1: 2 patients, Road2: 1 patient, Road3: 3 patients