def calculate_passengers_mass(n_passengers, passenger_mass):
    """
    Calculate passengers mass including driver [kg].

    :param n_passengers:
        Number of passengers including driver [-].
    :type n_passengers: int

    :param passenger_mass:
        Average passenger mass [kg].
    :type passenger_mass: float

    :return:
        Passengers mass including the driver [kg].
    :rtype: float
    """
    return passenger_mass * n_passengers
