How many ways can all players line up if Samuel has to stand in line first and if the centers have to stand together (there are no other restrictions)?
In training, the coach will classify players randomly into three groups of 
players each: the first group will practice free throws, the second group a game in defense, the third group a game in attack.
Calculate the probability of events:
Samuel and Jack will practice the game in defense,
Samuel will practice free throws, and Jack will play in attack
players: 
defenders, 
centres. One of the defenders is named Samuel and one of the centers is Jack. The remaining players have different names.
defenders, 
center?
girls and 
boys in a class. A three-member committee is to be chosen to prepare for a program. Calculate the probability that both sexes will be represented on this committee .
