10 physicists and 8 chemists gathered at the congress of natural scientists. Only one physicist is named Francis, only one chemist is Klemen. The participants of the congress will choose from their ranks a 5-member presidency, in which 3 physicists and 2 chemists must be. In how many ways can they do this if there are no other constraints?
Calculate the probability of the event A that at least one of the previously mentioned persons (physicist Francis or chemist Klemen) will be in the presidency, if the members of the presidency are chosen randomly from physicists and chemists.
